Some of you may recall that I did this with a t42p a while back, and now that I have a thinkpad again, I gave it a shot on my old board before I replaced it with a t60p board (wohoo, a dedicated gpu!). I used a 10K pulldown on FSA after removing the 10K pullup, but the laptop failed to post when forced to 200FSB.
Unfortunately, the t60p uses the same clock generator. I don't know if it was a limitation of my components or something else that cause the post failure. The board works as it did before after reverting it back to stock.
ICS954309 is the clock generator and the datasheet is freely available from the ICS site.