Motf bane, google up xeon pinmodding. Most of what you'd find would be about old stuff back when they were pga but there should be some good explanations. I wrote a decent article three years ago but the server went mia unfortunately. Google still has a cache of the writeup although the pictures (useful) are gone. You can find it at http://209.85.165.104/search?q=cache...lnk&cd=3&gl=us
It takes a long time to load for some reason, but I actually had to reference the cache today myself since I got a little rusty. Hope it helps.

Basically, bsel is a set of flags defined on the cpu that the motherboard reads to know what fsb to set as default. Input is measured in terms of high or low resistance. Thus, in the traditional sense, to achieve a high resistance from something that's originally low, you can use white out or nail polish or tape to cover up a land. In the pga days, it's be nail polish to insulate or just yanking a pin.

To make a high resistance into one of low resistance, one can either link it to a bsel of low resistance, or link it to a ground (vss).

It looks like from this technique as posted by op, it's been determined that you can link up a bsel that's originally flagged as low to a vcc (power) to bring it to high. I'm still thinking of the phenomena behind this myself, but it looks like it'd essentially be causing a relative resistance as seen by the motherboard to be high and thus be the same as isolation of the land/pin.

Hope this helps