I am also currently in discussion with Chris (of Tesla) on the exact registration process.
At this point my understanding is that I will send a check to Tesla in CA for the total amount including MA sales tax, title and registration fees.
They will send a package in return with Certificate of Origin, a check for the Registry (I assume), sales receipt, etc.
Once I have the VIN # (should be next week), my insurance company will email me the RMV-1 also need for registration. I am supposed to go down to the registry myself.
One point I have raised and am still awaiting an answer to, is who will pay the MA sales tax. If I have to go the the Registry myself then I should cut the check, not Tesla. Should have an answer on that Monday.
Lastly, I am concerned about the inspection sticker. The typical garages which do stickers around here can not be trusted. I have one other nice car which I usually take to the dealer....only slightly better than local garage
Will keep you guys posted.