copy the cstrike folder into your... Steam\SteamApps\"YOUR NICKNAME"\counter-strike source\ ... folder.

browse to your Steam\SteamApps\"YOUR NICKNAME"\counter-strike source\cstrike\materials\models\player\t_leet\jacketcolours\ folder and choose your favorite color.

copy the t_leet.vtf file into your Steam\SteamApps\"YOUR NICKNAME"\counter-strike source\cstrike\materials\models\player\t_leet\ folder

and enjoy it ;)