You can install it on mac, downloading the pak manually
, or try this http://www.codeweavers.com/products/#cxmac/
If you don't want to download that stuff, i uploaded the PlayersATP.ini from last Sam's Megapatch, but i don't know if may be buggy on an unmodded game https://www.mediafire.com/?udy2ppw8c9ryqdd
If you have any question, keep asking
I'll try to help you if possible.