I have a 2002 spi... how would a 2.0 swap from a normal 2005 focus go?

what would need to happen?

Your better off buying a 05, cause you'll need everything

the answer to all motor swaps.

Anything is possible with enough money.

Damn...alright thanks guys!

With any motor swap, the ideal situation would to buy a wrecked donor car. That way, you have wiring harnesses, brackets, gauge clusters, all the little things you would need.
Of course, that requires a lot of garage space and an understanding neighbour/wife/significant other!

It can be done, all depends on your skill level. Like was already suggested, get the most complete donor car you can get, you'll be glad you did. As per my reply to another swap question, I am doing one right now on a 2000 SE wagon. Good luck and don't listen to the naysayers that don't know shit... straight forward swap: engine and trans, ECU, wiring, fuel system, etc.