Been there, done that! It's real handy for all the junk that usually rolls around on the floor.
Which one are you referring to? I ordered one from the accessory catalog but didn't like it at all. No room and poorly built. The dealer was pretty good about taking it back and ordered in the open storage bin that is illustrated in the parts... . um, can't call it a catalog when it's on the computer.
Unfortunately, if you want to do the open bin the factory way, you must change the seat hinges on either side of the lower seat. These are *expensive*! If you are up to a little metalwork, you can probably fabricate your own brackets to fit.
Factory bracket part numbers are:
05012914AA and
05012915AA
These are for the '99 QC, but I doubt that they would be different for any other year. They are called brackets, but are, in fact, the whole hinge assemblies, right and left. They're easy to change.