the lower part on most seats i've seen has a locking mechanism. search in the center part of the left and right portion of the rear seat and under the cushion there should be a pull tab..pull and push the seat up..repeat on the other side. ..you can then access bolts for the back portion..
this is just theory.. i've had it in the cars i had before the corolla. as its 1am EST.. i can't go out side to verify this..