The JL 450/5 does have xovers for the front and rear channels, here are the specs..
-Channel 1 & 2 Crossover : Fully-Variable (50~5Hz), selectable slope (12dB or 24dB/octave) LP, BP or HP
Channel 3 & 4 Crossover : Fully-Variable (50~5Hz), selectable slope (12dB or 24dB/octave) HP
So will this work with my components bi-amped with the Pioneer F90BT? I am not sure what to set the crossovers to on my jl 450/4... Im guessing i wire the tweeters to channels 3/4 since the xover is HP only and my mids to channel 3/4 set to BP? Not sure what about the 12dB/24dB, what do i set those