You can set up your PIM import rules to download new patches or check for new patches nightly. You don't want to just do ever 3rd tuesday when microsoft releases monthly patches because you might miss a critical one. You can't automatically make them available because once the PIM is downloaded they show up in your console and you need to highlight the ones you want and then click 'stage' which makes them available. Altiris doesn't usually post the patches on their download location until the Wednesday mid-day after the day Microsoft releases them.

thanks networkchic