Well, you are unlucky enough to have the first PII that had a locked multiplier.
This is when intel started to turn into what i like to call an "a-hole company".
To unlock it you would need to open up the processor casing and make some manual circuit connections. But if you are going to overclock you probably want to take the casing off anyways beacuse it really sucks at heat transfer. Heres a guide on how to alter the PII pcb:
<A HREF="http://www.hardwarecentral.com/hardwarecentral/tutorials/895/1/" target="_new">http://www.hardwarecentral.com/hardwarecentral/tutorials/895/1/</A>
As far as your FSB, you should just take a closer look at your mainboard and try to read any silkscreen on it that may give a hint as to where the FSB jumpers are. You can try to expriment one jumper at a time to find which one sets FSB. Then when u find it u can begin to try to find a pattern to how the jumpers have an effect on FSB.
You certainly have your work cut out for you!
Our you could spend ~$55 to get a "slotket" converter and a celeron 533.
If you do decide to buy the new celeron make sure its a 533 and not a 533A or higher speed. These use the coppermine core and wont work on your system beacuse your mainboard will most definitely not support the lower voltages. Make sure the chip is PPGA and not FC-PGA so u dont get a coppermine.
P4's are good to pee on.