i assume you are talking for installation as harming the old bearings isn't usually a concern if you are tossing them in the round file (trash).
my vote would be heat the hub (not so hot you can't handle it) and freeze (the colder the better) the bearings for installation. they don't quite drop in but it helps.
Originally Posted by BobCWNC
So, will heating and beating on the bearing hurt it? (assuming I take a modicum of care)