no tricks to changing the seat belt buckle.. unbolt the seat from the floor and basically tip it to the side so you can get at the bolt for the buckle.. no need to remove the seat from the car.
the bolts for the seat to the floor are inverted torx if Im not mistaken (cant remember what size off hand) the bolt for the buckle to the seat is a regular torx (either a 40 or 45... its a big one)
good luck.