Upgrading a laptop processor

I have an IBM thinkpad 760XL laptop.
It has a intel 82437MX Pentium (r) processor which works fine, but I
cant install quite a few things due to the size of this.
I have managed to get hold of a 750mhz Pentium 3 processor, but need to
know if this can replace my old processor in this laptop.
AND, if I can change it, how do I do it?
Any help and advise would be greatly appreciated.
Thanks