yo man. actually its not that hard at all, depending on your level of knowledge on keyless/security. if i am correct still all the connections made by the factory are in red butt connectors. as long as the guy who put the cifford in didnt butcher the wires (as most people who dont do it for a living do) that you just have to find the wires. most of the connections should be in the drivers kick. i do install a/v into cars for cc and am very knowledable on this subject. but u know what they say. cant be sure without looking at it. feel free to try. you can do no harm unless the clifford install was incorrect. and of course you would need the factory oem alarm box (little black box). feel free to also post pics and ask for help......on the other hand if again the clifford was installed well or professionally than swaping to another aftermarket is extremely simple.
-alan