the front speakers are pretty easy... i'd give yourself 2 hours if youve never done it before though. You have to take the door panels off... which isnt hard... theres a total of like 3 or 4 screws in the panels, then it just pops off. The screws are in the arm rest areas... and in the door handle cup.

Ive never really paid much attention to the rear deck of the LX, but does the grille look sized for a 6x9? The plate that the 6.5 is mounted in, is that oval shaped (just a little bigger than a 6x9 speaker) and held in by 3 bolts?? If so, you can use a piece of rigid plastic, put a layer of dynamat or something similar on it, and mount the 6x9's in that... or you can use 1/4" MDF...