On my '92 SSEi, there are plastic keys on each rear seat handle that slide in to separate a set of plastic legs with barbs on the ends. When the key is pulled out, the two plastic legs can squeeze toward each other allowing the assembly to be pulled straight out. What usually happens is the plastic legs get brittle over time and break (or get broken when someone tries to force the assembly out) I think you need to pull the handle down on its spring to reveal the ends of the keys. They are about 3/4" wide and about 3/8" high. [edit: and one is the end of the garment hanger] You may need a pair of pliers to pull them out, or a screwdriver to pry them a bit to get them started. Just pull the keys straight out.
Don't attempt this with the car and the plastic cold. Warm the whole assembly up with a heat gun or a hair dryer if your car is cold. Once the assembly is free, gently tease the wires out 'til you see the electical connector; then undo it. There is also a plastic plate between the headliner and the roof, and for each set of legs that hold the assembly in place, there is a spring steel clip. This stuff must be installed properly, so keep track of where and how it goes together as you take it apart.
 said better and faster by the Randman!