You need to either convert to OBD1 or use the one of the output scripts used in Turboedit or another OBD0 editing program to activate VTEC ..

I would choose a OBD0->OBD1 Jumper harness and a P28

Then you need to wire in the VTEC solenoid to A4 on the P28 and jump A4 TO D6 to bypass the pressure switch ..