you can use the p28 ecu and get the Hasport conversion harness.

obd-0--obd-1, plug and play, basically, as far as the car will know, it WILL be obd-1.

and if you use the shift light on your tach, basically you're just using the shift light as an activation switch for vtec engagment. On a d16z, the factory vtec engagment is at 5500-5700rpm., so you set your shift light to come on at 5500rpm, as soon as the light comes on, so does vtec, BUT the shift light will stay on until redline, or until you shift. I wouldn't use this method though, i would just use the p28ecu and get the Hasport conversion harness. You won't have a blaring light on all the time, and also it will probably run alittle better, it will run like its supposed too.