I'm not sure whether my car actually has this feature (one of the reasons I
am looking for a manual), but on the United Malibu's web forum, one guy had
a posting of the programming procedure for the different modes of the
auto-lock feature.  Apparently this enables all the doors to lock, just the
drivers door unlock, or all four doors unlock when the key is turned to Off
and taken out of the ignition.  Or it can be disabled altogether.

The other feature he mentions is when you hit the Lock button twice on the
keyfob, you can program the horn to sound or turn it off.  Here is his post
which describes how to use both of these programming modes, however, neither
seems to work on my car.  My horn already sounds when the Lock button is
pressed twice.

http://www.unitedmalibus.com/forums/showthread.php?t=3024&page=3&highlight=remot
e+program

Scroll down to the last post on the page under the user "majorpain".

Thanks for any help,
Sharky