Pretty eash to do, just takes a little time. So with that here is what i did:
Pick two teams to edit, Make all the players on one team 7' 6" and all the players on the opposing team 5' 4". You can also play with the players sliders so you have them set up so your 7' 6" team are all beasts and the 5' 4" guys are really really bad
Now go to the settings page and turn down all of the AI's game sliders and turn all of yours up except the three sliders for shooting put those all the way down.
Now pretty much everytime you get the ball, just put up fade away shots from half court and odds are your 2 guys under t he net will grab rebounds all day, when they do pass it out and repeat the fade aways until one of htem has 51+ rebounds.
I did it on 20 minute quaters but odds are you can do shorter since one of my guys had 41 by half time.
If you have any questions or helpful tips please feel free to post, have fun and good luck