I have never done it on a Mazda, but with most cars you remove the seat cushion first then there are bolts that hold in the back. On my car you remove the cushion by pushing it down and back until the hooks underneath disengage. I suggest calling your local dealer.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's