Rockman.fr
Now, I recommend you start with a Rockman sustainer (100 or 200, doesn't matter 100 if you're on a budget) and rockman distortion generator. Use the Rockman sustainer for clean 1 and 2, that is your clean module, for yourOD use the DG, on EDGE and distortion. You're going to want to also buy a dual 15 band EQ I recommend the DBX 215, great little EQ for the price used, buy any will do. You're going to want to put the first part of the EQ BEFORE the Compresser of the sustainer, and tweak to your hearts delight. After the sustainer and DG I would put a Chorus/delay, and use the delay setting on 200ms (the higheset it goes) for making your chords really big and chunky. after that a Stereo Chorus Works great to fatten up your leads and chords on the "wide" setting. After all this put the second side of your EQ here and tweak some more. This will all run you about 650-750 USD on the used market. If you're really going for the Boston sound I recommend a LP style guitar with pretty hot pups (Scholz uses DiMarzio SDs) The best place to find the stuff is on ebay, but craigslist and gear ad's are always good places to look.
Other "rockmodules" I think you should have are the Stereo Echo and midi Octopus and midi pedal. Recommended not required.
I'll add more to this later. ask away!
PS. If you don't know who Boston is I won't be happy.