You'd need to modify the roster files so that they're compatible with NBA Live 06. Basically that means adding columns to the players.dbf file that are present in 06's databases but not in 07 and modifying values such as dunk packages. If you're a novice when it comes to DBF editing, it's not something I would recommend.
So I think we need to make a list of what's compatible with live 06 or what we need to change to do it. In the meantime can someone tell me what things from 2005 are compatible in 06. People are still updating 05 constantly on here.