Can the TT-50 be used with the BGM-100 to true a bench grinder wheel?
Sort of, but it takes a great deal of care and a little bit of ingenuity.
You have to put it on upside down and backwards (depending on which side of the grinder you put your BGM-100 on). :-\ The fork which insures proper alignment of the TT-50 cannot be used (on either side). You have to tweak the angle of the TT-50 so that the cutting tip is relatively flat to the grindstone. It is absolutely vital that you take very, very fine cuts off the grindstone -- much shallower than on the Tormek.
It is not a recommended application of the TT-50.