Jon, the numbing stuff is simply a lidocane/gel mix. My nurse thinks the numbing really isn't that good and the relief comes mainly from the gel. Comes in a syringe-like container sans the needle and they just put it into the opening of the urethra and wait a couple minutes. My "plumbing" has gotten so small in diameter after the repeated trips in and out that the regular-sized #14 catheter doesn't work for them. (Although the Doc is able to cram that sucker in 'cuz he's a guy, I think, and knows just how it feels to us guys....ha). But the nurses seem to be much more careful not to hurt us.
Last time a new nurse tried a #14, then a #12 and gave up, so the regular nurse came in with her #10 catheter and pushed it in in a flash...no pain. Didn't even feel it going past my prostate like usual. And the BCG goes in so fast the small one isn't really of any consequence. One caution is the small diameter could cause it to reverse itself while going in, so she always checks for urine flow back out before putting the BCG in.
I guess I'm fortunate since the only effects I seem to have is the constant urge to go for several hours after the treatment, but I can live with that.
One last thing, when I started these treatments, the nurse did mess around with a needle, trying to numb things down for me - didn't work. But I think that is a big waste of time since the needle stick is far worse than the catheter going down. I think the key here is to use a # 10.