Been out of the US for years, literally, but will be in Boston for a week. I realize however that even more than before, it is difficult to see a provider without references or one of these referral services. Any advice for providers out there as to how I can make an appointment? Is my TER handle useful at all? All my US references are retired...

Not all your reviews have retired.  I would e-mail whoever you want to see and ask what they need.  You can send a PM by TER to prove you are [the guy with 24 reviews on TER].  Once you pick out a girl, you can find out her [or her agency's] requirements.

Ask and you shall receive.

You have reviews and you can legitimately claim to have been out of the area.  You might reach out to Jill at RoomServiceGirls because she's been around for a while and will likely know some of your old friends even if they're retired.

Good luck!