I'm not really sure. All I know is there are loads of tiny little connections between the CPU and motherboard, so the operation would be really delicate. If you are really willing to do this, I suggest seeing a professional; it's not a really a DIY job. But, as
bbrosemer pointed out, if the processor isn't blazingly fast, there's no point in risking so much. If the CPU's messed up, it pretty much means a
new mac
If you are worried about speed, I suggest upgrading RAM, or getting a faster HD. I'm just about to order some RAM to put in my mac at home