Ensure that the Administration Server is not running.
Install the agent as you would in a stand-alone environment. See Installing the WebLogic Server/Portal 10 Agent.
Configure the agent classpath for the Administration Server. See Configuring a WebLogic Server 10 Instance With the Agent classpath and Java Options.
Start the Administration Server.
Configure the Agent Authentication Provider. See Configuring the Agent Authentication Provider for the WebLogic Server/Portal 10Agent.