A password can be set during remote installation using the ‘pwdService’ parameter as shown in the example below.  This sets the password with which the agent software on the remote computer is protected from unauthorized access.  In order to connect to the remote machine the password must be specified or access is denied.
 

An example of a command used for remote installation, including the pwdservice parameter is:  perfRSManager -i -host AgentHostName -pwdService MyPassword

In Silk Performer 2011 there is a known issue which causes this parameter not to take effect during installation, meaning the agent can be connected to without providing the correct password which was set during installation.  This can be resolved with the application of hotfix SP83_HF7.