there is 2 ways to do the rear seat.
You can take the foam off the metal bracing of the newer seat and put it on ur existing bracings. This will then require no mods to the brackets that hold the rear seat down, nor required engeneering for the brackets of the newer interoir being modified.
2nd way u modify the brackets that hold ur new seat down. You can then use the fast clips like the VT use to quickly remove the seats.
the fronts are not as hard. just change the runners from ur existing seat onto ur new seats.