If there are enough people on later tonight that are game then we could do it. The pit's probably deep enough as it is, plus there's a mineshaft ~8-10 blocks beneath the floor that I
really don't want to fall into while doing battle.
Drew - if possible I try to come in from the sides 1 block below the spawner. That way it's easy to place torches on the spawner through a 1 block hole cut in the wall. More difficult with cave spiders, but if you can place a torch on top of the spawner from above beforehand it helps minimize the spawning a bit.