Pat this is one that you probably cannot leave to you mechanic alone. Best to call an avionics inspector at your FSDO, no the maintenance or airworthiness inspector you mechanic would probably deal with. Then send him the paperwork, then call him to see when he can make it out for an inspection. If he balks, there are currently more than a dozen installations in the US that I am aware of, including a maintenance inspector in the Anchorage Alaska FSDO.
Hope this helps
Jack
________
Live Sex