I don't know if there's any way to get it open with it still guarenteed in working order... although I'm sure there's a couple ways, mainly involving brute force that would leave the inside in questionable condition.
I'm not concerned with it being functional, it was from a computer given to me by a
customer who bought a new pc. I'm tossing out the case, and using the parts for
possible mod ideas (like that case made out of motherboards). But I'de like to be
able put the cpu back together.