Would you like any discussion about finding a way to burn your house? Or you could check the intention of that discussion first? I mean - moral ground.
Or, it simple - use google and find it. But that guys are smart enough to target only phones which are commercially profitable to sell, they don't stole anything which has no market. If there is no known way to change IMEI then that market doesn't exist for N900 ... or at least it is restricted by some 3rd world countries without IMEI locking.