I should also note having just looked at my trunk, I don't see any metal loops for attaching bungee cords (how I held the tC box in). I'll have to look into securing it, but I'll likely use some sort of bungee cord system. On the square box, I used small screws into the outside of the box as anchor points or pivot points for the bungees. It held secure, didn't move around, and didn't interfere with the movement of the woofer. This one has a metal grate on it, but I'll still likely do the same thing once I find some appropriate points to secure a bungee too. Otherwise it would be sitting loose in the back. Whenever I get it (waiting for tax return), I'll post up how I have it installed.
Edit: In the tC...
Eventually, I moved it to the passenger's side with the speaker facing the driver's side. In that position, I wrapped the left bungee over the top screw and hooked it to the right one. Right bungee hooked onto to loop of first bungee. Also, pictured is my old, old JLW3v1 from 2001 which lasted me until about 2 years ago when the cone and ring started to separate. Was replaced with a 12W3v3 (same box). Got 9 years of hard use out of that first one, and that was with the old crappy foam materials. I will buy JL all day any day.