Hey Evan, where'd you learn that technique?
Mix the bleach until you get a (no kidding) weak pee color. It's better to have a slower working bleach, since it's much easier to control.
When the print comes out of the fix, rinse off the print, then squeegee it. Rinsing the fix off will help soften the edge where you're bleaching. If you don't rinse the fix off, the bleach can work too fast, which will leave a sharp edge. In other words, you'll be able to see where you've bleached.
I've never used cotton balls - I always use brushes, and place the print on a PVC sheet mounted on a stand in my sink. Light above, hose with running water handy. I always run water over the area directly below the area where I'm bleaching to prevent any 'bleach over'.
It was alluded to above, but I change the orientation of the print on the board so that a dark area is always below the area I'm bleaching (if possible). Then, if a bit of bleach runs off the area being bleached into a dark area, you won't see it since it takes much longer to affect a dark area.
Once you've bleached for a bit, return the print to the fix to neutralize the bleach. Then repeat the above steps until you're done. Generally speaking, it will take multiple applications - you don't want to throw the long bomb on the first play, since chances are, you'll bleach too far and ruin the print.
It's also important to understand that fix will accelerate the bleaching process - this is why you have to rinse the print off first - so you can control the process. However, it also means that when you return the print to the fix to stop the process, it can cause the bleaching process to proceed past the point where you bleached to. This is why you never bleach until it's 'right' - bleach a bit, return to the fix, and iterate. In effect, you want to 'sneak up' on it.
It can be a scary technique when you're bleaching a print that requires a bunch of manipulations under the enlarger, but once you've done it a few times, you'll have another valuable tool in your toolbox.
I learned this technique from Bruce Barnbaum - if you pick up his How-To book, a full description of how he bleaches is contained therein, along with a lot of other very useful information.
Good luck!