Pretty sure that it isn't just pulling out our Civic seats and replacing them with the ITRs, but I don't think it's that hard. There's a thread on HT about swapping them into a EK, and it has pics and what not, might give you an idea of what will be involved. If I remember correctly four doors would want to use the seats from the ITR coupe, not the sedan, but it's been a long time since I messed with seats.
For some reason I am remembering that in order for it to go in smooth you need the ITR four door rear seat bottom, and the ITR coupe rear seat backs for an hatch, and the opposite for the four door. The ITR sedans had a wider bottom, and the coupes had a narrow bottom, and in a hatch the ITR coupe bottom left a gap on the sides of the seat bottom. I remember when I had my coupe ITR rears, I need to get the ITR sedan bottom to not have a huge gap.