You must have a look at the MOB manufacturers website and see what the latest revision of the BIOS they have issued and download and flash the new BIOS. Normally it will give a brief description of what the latest revision fixes and what it will support CPU wise. Failing that if the manual doesn't say, have a look at what the jumpers will do with regard to FSB speed (66, 75, 100 etc)and Multipliers (2x 3 x..10x) that should give you some idea of what you can do.
Hassel unfortunately it is getting more and more difficult to get a P11/111 slot 1 CPU as the new CPU's use a different interface (back to sockets) however you can get an adapter to convert from a slot 1 to the new socket types.