WARNING: This page is about a different car, the 2003 Mazda Protege5 and 2003 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.
Remove the trunk end trim.
Remove the bolt, then child restraint seat anchor.
Install in the reverse order of removal.
Fig 1: Removing Bolt And Child Restraint Seat Anchor (5HB)