You'll be able to hit "Get FSB" move the sliders, hit "Set FSB", and see a change in CPU speed in cpuz.
Most of them will simply fail.
Some will crash SetFSB.
Some will crash the whole system (reboot, it'll be fine), and a select few will hopefully work just fine.
The numbers don't necessarily need to be accurate, if it thinks you're adjusting from 600fsb to 610fsb and is really from 266 to 276 that's fine, as long as it really adjusts the fsb.