We just bought a new house that came with a security system. The
system is quite old, so we're probably going to remove it and replace
it with something a bit more modern. Since I am currently laid off we
cannot afford a new system at the moment. Instead I am focusing on
getting the current system up and running. I have already managed to
clear the memory by short circuiting the reset pins next to the EPROM
and reset the password (default was 1234). The only problem is that in
clearing the memory, all of the sensors have been lost to the system.
The system is an "ITI RF Commander III". I have the owners manual, but
it says nothing about adding sensors. Where can I find the
installer/technical manuals for this system?

This site may be helpful to you:

http://tech-man.com/

Yes, I have looked at tech-man.com already. I am currently trying to
get an account on there to look at his tech manuals. It also happens
that my company has to work on the same system in an urban data center
project we just got. Apparently these RF Commanders were very popular
at one time.