I've done this exact swap myself, so it can be done. involves a bit of cutting, drilling, shimming etc to make it work, but it's not very hard. CRX rails will not bolt onto the civic floor though, so you have to adapt the crx seat to the civic rails. Either that or just do some welding. Than you would be able to make the crx rails work, and wouldn't have to hack the stock seats at all. It's not a reversable swap though because you will have cut the stock rails completely apart, so if you want this to be reversable or plan on selling the stock seats, then I would go the welding route, or at least make some sort of adapter to adapt the crx rails to your floor. for example, the crx rails are narrower, not quite as long, and the rear mount tab on the rails is on a different angle than the stock rails.