On the HAmotorsports site I found this;
"On your engine harness, locate the Vtec oil pressure switch wire (this wire comes from the OBD1 ECU pin D6). Simply tap this into the Vtec solenoid valve wire (the Vtec solenoid wire comes from OBD1 ECU pin A4). Do not cut the Vtec solenoid wire, simply connect the pressure switch wire to it.

That's it??

Sounds too easy