You can use Ambari to deploy AMS and use pre-built Grafana dashboards to monitor your cluster. Note: Since the cluster is not Ambari managed, sizing AMS might need manual work, the Apache Amabri wiki has good amount of detail.
The catch is configuring daemons to write to AMS, which is basically editing the configs files, I would go about actually creating a dummy sandbox cluster and copying over and modifying the configs like: hadoop-metrics2.properties.
Can you file an Apache Jira for missing documentation around this? Myself / @Aravindan Vijayan can add details on it which can be added to wiki. Feel free to contribute to the same.