First off you could try to find sr5 leather seats and they will be manual. Otherwise you just run a power wire to the seat and ground the ground wire and that is it.
I 2nd looking for some stuff in a junkyard, it would give you everything you need but if you can get passed the electric seats katzkin makes an exact replacement to your seat.
I've done some upholstry stuff in the past for my last car and it's pretty tough to just replace the material but it's possible and it looks dang good! Good luck with the project!
Are you gonna do the door panels too?