[nlafrance]

I'm in the same boat, nearing completion of my Cobra and I live in MA.
From what I've read on the Mass RMV site, you first set up an appointment at a MAC to get a mechanical review of the completed car. If you pass the MAC review, you will be able to register the car and go for a normal inspection at any station that does inspections. There are a half a dozen or so MAC's in the state, find one near you and call them for your appointment.
I plan on doing this in the next couple of weeks. I'll take notes and post them for others in the forum. Good luck on your build!
Neal