Go to "Options" and enter the following in the Cheats menu for the desired effect--

EAASFSCT : Unlock AFC East All Stars
WAEFSCT : Unlock AFC West All Stars
NAOFRCTH : Unlock AFC North All Stars
SAOFUCTH : Unlock AFC South All Stars
NNOFRCTH : Unlock NFC East All Stars
NNAS66784 : Unlock NFC North All-Stars
SNOFUCTH : Unlock NFC South All Stars
ENASFSCT : Unlock NFC West All Stars Reebok : Unlock Reebok Team

EAField : Unlock EA Field

The following only work in Quick Play mode--