Ok guys here's some more detailed pictures about the Celica seats installation with their own rails:
First we have the passenger side as example, here is the front hole close to the center console and as you can see in the picture I had to make it wider:
Door side front hole, here you have two choices either make a custom bracket as I did here or custom weld bracket as I did on the driver side, both will work good, btw in order to be able to turn the hole bracket, You will have to remove the factory spot weld with a drill bit as you can see in the picture then just some small hits with the hammer and you should be able to turn it around as I did here:
Driver side with custom weld bracket
Door side rear hole, as you can see again you have to make it wider in door side direction, in that way you will get a straight alignment for the seat
Finally the center console side rear hole, make sure to take off this bracket from your old CSM seats (it is the only one that can be unbolted), make the bracket hole wider in the center console direction, this will help to put the seat far from the center console then you have to delete the Celica hole bracket from this side, drilling both of the pins from this bracket and the center spot weld will do the job, now you just mount the rail over this bracket and you can either weld it or leave it as is (as I did)...
Now the Seat Belts, rid of the plastic covers from this section of the Celica seats, remove the Celica seat belt lock then install the CSM ones in the same direction as they were on the original seats:
Hope this helps in case you find a nice set of these, I like them because they look pretty sporty and they aren't that expensive as Evo Recaros...