WTF is B#???
Isn't B# actually C? (Homer Simpson's Barbershop Quartet was named the Be Sharps, I think...)
I've got some things tuned down to C#, and that's pretty low, 3 semitones down from E.
If your guitar has a tremolo, I'd recommend against making any changes yourself. If it has a Floyd Rose type (floating) tremolo, you DEFINITELY should not do it yourself.
You can probably do it, but turning back will be a bitch. As stated above, you need larger strings to keep the tension higher at lower tunings. You can get custom sets through most dealers.
Larger strings cascades the following chain of events and modifications. You must accomodate for the larger strings at both the nut (on the headstock where the strings meet the fretboard) and at the bridge/saddle (on the guitar body at the other end of the strings, past the pickups). The slots on the nut will need to be widened, NOT DEEPENED. The bridge saddles may or may not need to be widened depending on your guitar. The neck will need some more tension to compensate for the extra strings, and if you have a tremolo, it will probably need more or tighter springs. Then you'll have to reset the intonation. This involves fine tuning the string length so that fretted notes are correct pitch, by adjusting the bridge saddles toward or away from the nut.
If you do not like things, changing back will mean replacing the modified nut and saddles.
This page may help you understand some of the concepts, it isn't exactly what you are doing, but is very similar.
Basitar and Guitbass
My advice is to find a junker with a fixed bridge (not a tremolo)and experiment, or if you have the bucks, get one of those previously mentioned guitars that is made for lower tunings.
Queue