i've been working on my case, and if you have a table saw, that's great, if not, just use a knife. score it, and bend over a table or something, the break is pretty clean. the guiding thingy dremel makes workes pretty good. and no need for a second set of drill bits, just make damn sure that when you drill through completely, do not push hard, the hole will crack if you push through the other side, just apply light pressure, and everything will be fine.
good luck!
oh, and if you don't want to mess with soapy water, imho lube is not needed. I actually use my dremel at it's highest speed, cut, melt off what you don't need then finish with a fine grit sandpaper.