You need to gound the Vtec Pressure sensors black wire to a good gound source then run the Vtec Solonoid's green/yellow wire and the pressure sensors blue/black wire into the passenge compartment.
Connect the green/yellow Vtec solonoid wire to the pin A4. It is unused in your harness right now. Harness "A" is the big first harness and pin location 4 is the second slot over on the bottom row. It goes zig-zag pin A1 is a brown wire so A4 is under it to the the right next to the yellow wire (A2)
Connect the Blue/Black pressure sensor wire to pin D6. It is also blank in your stock harness. The D connector is the third connector directly opposite the A connector. There is no C connector in OBD-1.
Remember the pin locations go zig-zag. So it's 1 up and 2 bellow it. So think of it like this odd number are the top row and even are the bottom row. So D6 is three spaces over on the bottom row of the thrid harness.
I hope this wasn't to confusing. If you want email me at firstname.lastname@example.org
and I'll try to explain it better.
But that's all you need to do. Good Luck.