The TA22 and RA23/28 seats are almost identical apart from the rails and rail mounting points.
To put 23/28 seats into a TA22, you will need the rails and seat base from a TA22, you will have to dissasemble both sets of seats, and transfer the bottom metal frame from the TA22 seats over to the 23/28 seats then reassemble, and they will then bolt into the 22 using the 22's rails
To dissassemble the base you will need a pair of side cutter pliers, to cut the little bull rings. To reassemble you will need some wire rings and a wire ring tool. I got all of these from my local Mitre10 store.