I dont think he can use the p28 unless he swapped harness'. And if that was the case, than he would not need to run vtec wires. Also, it is in an obd0 car (91 crx).
If you have your stock harness and want to run obd1 you will need a jumper harness for the ecu and vtec wires will have to be run to the ecu.
Search the threads for vtec wiring, it is covered here im sure.