Got mine from Livefastmotors. Hollywood is correct, use their sprocket or the holes won't line up. They are a bit pricey, but very well made, so worth it. It takes alot of the torque away from the spokes. Good luck!!
I also am using the Livefast Clamshell Hub, I'm using a stock 44t sprocket for a schwinn skyliner and a 33t sprocket from spookytooth...drilled both without any issue. I just used a drillpress at a speed of 400rpm and lots of cutting oil... no issues and actually looks pretty neat. Thinking about making more speed holes. I have a couple of picture in graucho's link.