#作業の流れ
1.IAMロールを作成する。(「AmazonEC2RoleforSSM」と「CloudWatchAgentAdminPolicy」)
2.サーバーにCloudWatchエージェントをインストールする。
「Systems Manager」>「Run Command」>「コマンドの実行」から、「AWS-ConfigureAWSPackage」を実行する。
※コマンドのパラメータの Name に AmazonCloudWatchAgent と入力します。

3.CloudWatchエージェントの初期設定
Windowsサーバーにログインし、「C:\Program Files\Amazon\AmazonCloudWatchAgent¥amazon-cloudwatch-agent-config-wizard.exe」を実行する。
色々と設定値を指定する。
以下、設定ウィザードのサンプルです。

=============================================================
= Welcome to the AWS CloudWatch Agent Configuration Manager =
=============================================================
On which OS are you planning to use the agent?
1. linux
2. windows
default choice: [2]:
2
Trying to fetch the default region based on ec2 metadata...
Are you using EC2 or On-Premises hosts?
1. EC2
2. On-Premises
default choice: [1]:
1
Do you want to turn on StatsD daemon?
1. yes
2. no
default choice: [1]:

Which port do you want StatsD daemon to listen to?
default choice: [8125]

What is the collect interval for StatsD daemon?
1. 10s
2. 30s
3. 60s
default choice: [1]:

What is the aggregation interval for metrics collected by StatsD daemon?
1. Do not aggregate
2. 10s
3. 30s
4. 60s
default choice: [4]:

Do you have any existing CloudWatch Log Agent configuration file to import for migration?
1. yes
2. no
default choice: [2]:

Do you want to monitor any host metrics? e.g. CPU, memory, etc.
1. yes
2. no
default choice: [1]:

Do you want to monitor cpu metrics per core? Additional CloudWatch charges may apply.
1. yes
2. no
default choice: [1]:

Do you want to add ec2 dimensions (ImageId, InstanceId, InstanceType, AutoScalingGroupName) into all of your metrics if the info is available?
1. yes
2. no
default choice: [1]:

Would you like to collect your metrics at high resolution (sub-minute resolution)? This enables sub-minute resolution for all metrics, but you can customize for specific metrics in the output json file.
1. 1s
2. 10s
3. 30s
4. 60s
default choice: [4]:

Which default metrics config do you want?
1. Basic
2. Standard
3. Advanced
4. None
default choice: [1]:

Current config as follows:
{
        "metrics": {
                "append_dimensions": {
                        "AutoScalingGroupName": "${aws:AutoScalingGroupName}",
                        "ImageId": "${aws:ImageId}",
                        "InstanceId": "${aws:InstanceId}",
                        "InstanceType": "${aws:InstanceType}"
                },
                "metrics_collected": {
                        "LogicalDisk": {
                                "measurement": [
                                        "% Free Space"
                                ],
                                "metrics_collection_interval": 60,
                                "resources": [
                                        "*"
                                ]
                        },
                        "Memory": {
                                "measurement": [
                                        "% Committed Bytes In Use"
                                ],
                                "metrics_collection_interval": 60
                        },
                        "statsd": {
                                "metrics_aggregation_interval": 60,
                                "metrics_collection_interval": 10,
                                "service_address": ":8125"
                        }
                }
        }
}
Are you satisfied with the above config? Note: it can be manually customized after the wizard completes to add additional items.
1. yes
2. no
default choice: [1]:

Do you want to monitor any customized log files?
1. yes
2. no
default choice: [1]:

Log file path:
C:\ProgramData\Amazon\AmazonCloudWatchAgent\Logs\test.log
Log group name:
default choice: [Logs¥test.log]

Log stream name:
default choice: [{instance_id}]

Do you want to specify any additional log files to monitor?
1. yes
2. no
default choice: [1]:
2
Do you want to monitor any Windows event log?
1. yes
2. no
default choice: [1]:
2
Saved config file to config.json successfully.
Current config as follows:
{
        "logs": {
                "logs_collected": {
                        "files": {
                                "collect_list": [
                                        {
                                                "file_path": "C:\\ProgramData\\Amazon\\AmazonCloudWatchAgent\\Logs\\test.log",
                                                "log_group_name": "Logs¥test.log",
                                                "log_stream_name": "{instance_id}"
                                        }
                                ]
                        }
                }
        },
        "metrics": {
                "append_dimensions": {
                        "AutoScalingGroupName": "${aws:AutoScalingGroupName}",
                        "ImageId": "${aws:ImageId}",
                        "InstanceId": "${aws:InstanceId}",
                        "InstanceType": "${aws:InstanceType}"
                },
                "metrics_collected": {
                        "LogicalDisk": {
                                "measurement": [
                                        "% Free Space"
                                ],
                                "metrics_collection_interval": 60,
                                "resources": [
                                        "*"
                                ]
                        },
                        "Memory": {
                                "measurement": [
                                        "% Committed Bytes In Use"
                                ],
                                "metrics_collection_interval": 60
                        },
                        "statsd": {
                                "metrics_aggregation_interval": 60,
                                "metrics_collection_interval": 10,
                                "service_address": ":8125"
                        }
                }
        }
}
Please check the above content of the config.
The config file is also located at config.json.
Edit it manually if needed.
Do you want to store the config in the SSM parameter store?
1. yes
2. no
default choice: [1]:
2
Please press Enter to exit...

※ここで指定した内容が、Systems Managerの「パラメータストア」に格納されます。
一つ注意点としては、「Log file path」を「C:\ProgramData\Amazon\AmazonCloudWatchAgent\Logs」配下のファイルにすることです。
(他のパスを指定するとおそらくログが出力されないです。)

4.EC2のIAMロールを変更する。(「AmazonEC2RoleforSSM」と「CloudWatchAgentServerPolicy」に変更する。)

5.設定をインスタンスに適用する。
「Systems Manager」>「Run Command」>「コマンドの実行」から、「AmazonCloudWatch-ManageAgent」を実行する。コマンドのパラメータの Optional Configuration Location にSSMパラメータストアに格納した設定値を入力する。
デフォルト値は「AmazonCloudWatch-windows」。

以上になります。

ご参考までに、以下パラメータファイルのサンプルになります。

{
	"logs": {
		"logs_collected": {
			"files": {
				"collect_list": [
					{
						"file_path": "c:\\ProgramData\\Amazon\\AmazonCloudWatchAgent\\Logs\\test.log",
						"log_group_name": "test.log",
						"log_stream_name": "{instance_id}"
					}
				]
			}
		}
	},
	"metrics": {
		"append_dimensions": {
			"AutoScalingGroupName": "${aws:AutoScalingGroupName}",
			"ImageId": "${aws:ImageId}",
			"InstanceId": "${aws:InstanceId}",
			"InstanceType": "${aws:InstanceType}"
		},
		"metrics_collected": {
			"LogicalDisk": {
				"measurement": [
					"% Free Space"
				],
				"metrics_collection_interval": 60,
				"resources": [
					"*"
				]
			},
			"Memory": {
				"measurement": [
					"% Committed Bytes In Use"
				],
				"metrics_collection_interval": 60
			},
			"statsd": {
				"metrics_aggregation_interval": 60,
				"metrics_collection_interval": 10,
				"service_address": ":8125"
			}
		}
	}
}

参考にしたサイト：
https://dev.classmethod.jp/articles/monitoring-windows-eventlog-by-cloudwatch/