Remote Start on a 2004 Chevy Impala

I recently purchased and had installed a Avital AviStart 4100 remote start & keyless entry unit into my 2004 Chevy Impala.  Unfotunately, the installers only installed the remote start functionality of the unit, leaving the door locks, trunk latch, and defroster functionality uninstalled.  I now have two remotes that I have to carry around for the same vehicle, since the buttons on the Avital remote for the door locks and the trunk are inactive.  The installer told me that I would need a serial data bus interface to add that functionality to the Avital unit, but I read on a few forums that it would be a simple "relays and resistors" installation.  I've done some installing before (mostly two-way radio and cellular equipment) so I have an idea of what's involved.  Can somebody steer me in the right direction as to what hookups I need to make in order for these functions to be active?  Any help would be greatly appreciated.  Thanks to everybody in advance.

The outputs for lock and unlock on the avistart4100 are negative.  You will need two relays and a 470 Ohm resistor to get the locks to function.  The impala uses a one wire lock system.  Lock is negative trigger through a 470 Ohm resistor.  Unlock is a straight negative trigger.   The lock/unlock wire is ORANGE / Black and is found at the BCM, gray 24 pin plug, Pin B3.  I hope this helps to get you started.