rear defrost, 2002 saturn

just curious if anybody has experience with rear defrost i have a skytek astra 4000wrs2 2 way remote start car alarm

it doesnt have a defrost output but it does have aux channels. no the question is on my suburban i have tested the defroster switch and it seems to need a short positive pulse then it start the timer relay within the vehicle.is this the case in all vehicles?I am going to be installing this in a 2002 saturn l series and just wondered if i could send a pulse from the trunk out pput wether it needs a neg. or a pos. through a relay? is this possible to do or does the defrost need a latched output? with the 4000 the latched output stays on no matter what until you press the button again. any help would be nice thanx. http://scytek.net/pdf/product_astra_combo_4000RS-2W-1_manual.pdf