Use Group Policy to deploy your agent- i.e. startup script
or install the agent to the machine and remove the agentguid key from the registry before creating your image.
You can install it manually, if nothing else.
Log on to the machine and then bring up a command prompt and do a runas command to bring up an administrator command prompt. Once that is done, install the agent using the command line: framepkg /install=agent You will get a prompt about something happening behind the scenes. Click OK or whatever and then it will show you the agent install dialog. When that is done, it will take you back to your normal desktop and the agent should be installed.
I did this some time ago. Hopefully, I've recalled it correctly. I'm not at work right now or I would've tested it before I spoke.
Sorry I can't be of more help.