I just bought a new m798 mayhew softball bat, and was wondering what you think the best way to break this thing in so it will be dropping BOMBS??

That is a composite bat. You break it in by hitting about 200 softballs. Have your coach use it when doing infield practice. 200 hits shouldn't take long if you practice regularly. Never hit pitching machine balls (the ones with dimples) or wiffle balls with it. This may lead to breaking.

Some people boil their composite bats to break them in, but it will shorten the life of your bat.

Practice hitting the rubbery batting cage balls... (BCB's). Beware that while this helps breaks a bat in...the warranty may not cover damage...so hit lighter if you are a masher.