What CRX is it going into???
If it is going into an SI or an HF, you can use your stock wiring harness and wire in your VTEC solenoid and knock sensor. If your CRX is a DX, you'll have to do some wiring to convert from DPFI to MPFI and you will need an injector resistor box off of either an SI, HF, or 90-92 Integra. You will definetly need the ECU for the B16 which is a PR3. Also, if you are swapping into an HF CRX(not sure if this is true for B16, but it was for my LS swap) you might need the steering knuckles and hubs off of an SI or DX or 90-93 Integra front brake assembly(which is what I used, worked perfect+bigger brakes.)
If you have the time/money, check all necessities. Take off everything and check everything. Replace all gaskets, water and oil pump, all belts, take alt & starter to get checked. New plugs and wires. You know, just the basic tune up if you can't afford to go through the whole motor. If the motor came from Japan though, you probably don't have to worry too much. Just be sure to CHECK ALL SENSORS!!!! I always read about people with broken sensors on their B16's when they get shipped.
Hope this helps, feel free to ask anymore questions you may have, I'm sure I missed something.