As mentioned you're going to have to drill the firewall for the clutch cable and pedal. There should be metal stampings in place for a clutch pedal, all you have to do is just drill out the holes where the studs and cable go through.
If you want a clean cable hole, get a knockout hole punch. It'll give you a nice clean cut with no holes. I forget how I did mine in my B14 but it wasn't the cleanest and if I were to do it again I'd definitely use a hole punch of some sort.
IIRC you will have to either install a manual brake pedal or trim the old one. I trimmed mine.
With wiring you will have to either wire the clutch interlock switch into the existing harness or just bypass the switch and relay and connect the two bigger wires off the relay together.
Aside from that most of it is just swapping parts over - transmission mount, associated transmission brackets, shifter linkage. Not sure if auto SR20s share the crossmember with manual SR20s but on my GA I had to swap it over to a manual crossmember. Obviously you have all the parts already which makes it much easier. You might even want to just swap the harnesses instead of messing with any of the wiring.
This is going off of the top of my head so I'm definitely missing specifics but hopefully it helps.