Always use a relay, it just makes things work better. If you need I can link you to a relay diagram just let me know if your going from pos. to a neg. or what not.
If you check this link
http://www.techsupportforum.com/automotive-center/car-audio/167234-alarms-remote-starter-manuals.html
It shows a 5902(probably the same harnesses)On the H2 harness H2/5(AUX three output) a white wire with a black trace on it. It shows it puts out a negative so you may need to invert it to a positive. Radio shack sells relays and such.
* NOTE: Make sure you have the same Harness first!!!!!!!
I'm pretty sure it is, just has different features.