Kyle - I don't think Iron Mike did anything specific for legs (like weighted squats) simply because the "ring work" portion in boxing often includes hand drills, rope work, footwork drills, etc. The footwork drills, back when I was a kid, included "fighter squats" to ensure proper motion along with slipping. Not just your head moves when you slip punches - your body, via lateral movement, moves too, and the legs provide all the meaningful motion (up & down as well as front-back, side-to-side).
Keep us posted on your progress!
I looked up "batman workout" and got a bunch of stuff on Christian Bale when he was training for the Batman role. Lots of plyometrics and heavy resistance to put on the pounds - he had only 6 months after finishing "The Mechanic" (he starved down to 121 pounds [losing over 60 from his normal weight]) to be ready for "Batman" (he gained, in that 6 months, over 100 pounds of muscle...from 121 to 230 - THEN had to cut down to 190 because the director said he was too big!).
GoodSam - Me? I'm not training for any competitive event. I just like to train!