you can combine any motherboard with any other part of a psp without changing anything
but i do know that the memory stick/wifi board has a mac address on it that is compared with one that is stored in the motherboards flash, i dont know which one gets changed, the one in the flash or the one in the wifi as i have never had to do it before but tools have been made to let people do this im sure a quick search of the web will find you either the program or the information that you need to get the program, i will have a quick look for you now
EDIT:
well that was comical i searched google for
psp mac address fixer
and the top result was
LINKthere you go read up on that