That's the good thing about just having an A&P. You need an I/A (inspection authorization) in order to complete that task. Of course you can help, but then again any Joe Schmoe can help. Unless it is very light equipment that you are working on, there really isn't too much that an A&P can sign off.

I did the repair station thing for GDAS for a few years and worked on a few privately owned jets myself and I too was pretty limited as to what I could legally sign off under my own A&P.

Just don't get the I/A or make no mention that you have it and all you are good for is your knowledge of the systems and maintenance operation which can be pretty valuable to an operator if you ask me.