The MR2 brackets have a wider bolt pattern than the celica and paseo setup. The rear brackets do fit the paseo front hubs, and the MR2 front brackets have plenty of room to drill 1 hole in each bracket and thread it. However the thickness is still a minor problem.
This is the MR2 front, MR2 rear & a Celica rotor
This is a Paseo bracket bolted to the rear of an MR2 to show fit.
This shows how far off the Paseo bracket is on the MR2 front.
Here's a pic of the Paseo rotor by the MR2's
Here's the difference in centers.
Also the rotors were marked 17mm min thickness on Paseo, 24mm on MR2. I'll take the MR2 rotor to parts store soon and compare to other toyota rotors.