You need to make a press to remove the bearings. Length of tube (or large socket) with od sufficient to rest against housing and id large enough to accept removed bearing, piece of flat metal, length of threaded rod, socket for other end with od sufficient to enter bore and press bearing out, couple of nuts. Simple stuff. Similar (minus tube) to press the new ones in. Heat doesn't much help for this. Seals are going to be trashed when you extract them so thats not an issue.