You have to:
1. mis-match (1CRX Inner & 1Civic Outer) the rails
2. make 2" extension brackets for the inner rails to reach
3. and 1" spacer (Lug Nut works good) on the inner rear mounts to lift the bracket a little and level the seat...

Not that hard... You have to make 2 extension brackets for each seat. Just some flat steal with holes spaced about 2" apart.

I Had 89 CRX Si seats in my 91 Hatch that I sold Steve-O, but I kept the seats and I sold Sky the brackets and converted some 89 CRX seats into his 88 Hatch.