replacing heater core? on 1998 Nissan Altima

how do i go abouts replacing my heater core? i really dont want to have to pull the whole dash out

Asked by for the 1998 Nissan Altima
5.9 hours in the book without evac and charge ac.
if you unbolt it and move it to seat, it does not have to come completely out. there is no other way to do it.