Find the electronic box for this thing on the car and see if there is a phone number or address. Then do a Google search and call, write or email them.
If nothing found and you are replacing the system with another, have the shop doing the work remove the old system. It is not that hard and the shop needs to get to the same wires as where the old unit is installed. Having two systems may make using the system difficult or impossible.
You could pull it yourself, suggest first you download the correct year wiring diagram from the link below. With the diagram you can see what color wires go were. The device installs in-between a few key wires and is hooked up to 12V power.
http://oregonstate.edu/~tongt/camry