i have the exact same setup on a 2010 6 speaker system... JL 500/1 powering a jl 10w6v2 and TPLSM3 enclosure, i just used the JL stereo to rca cable
http://www.crutchfield.com/p_136CLR2...W.html?tp=2610
and hooked it from the rear speakers straight to the amp, no PAC or anything, the JL amp does a good job at filtering low/high inputs and frequencies... now i just need to get some tweets in the car :P