Basically you're gonna get some aquarium parts for this ;) a brass part that joins 2 airline hoses together (union) is used to tap into the air pump supply. Use a small drillbit to make a pilot hole in the hose exiting the rear of the air pump, and insert your brass tap with hose (vacuum hose) on it. You're gonna get an aquarium air valve, one with 1 inlet and 2 valves/outlets on it. Ill explain why in a minute.

Run your airpump supply to the inlet of this valve. Run more hose from one of the outlets to the 6PI nipple on the motor. Open this valve about halfway, and the other about halfway, open-air vented. The reason you must vent/dump some air constantly is because the airpump is always generating some pressure. Since the 6pi system is (supposed to be) airtight, once theyre pressurized (open), they wont want to return shutsince the airpump is still spinning some pressure on them...having an air dump allows the pressure to bleed quicker and allows them to shut more normally.

IT WILL take some adjustments of both valves to obtain a decent working setup. Opening the 6pi valve more makes them open quicker, and opening the dump valve more makes them close quicker, though having them both too far open makes neither work well...it'll take you 20-30 minutes of playing around to get it decent. Grab the throttle and rev the car up to see what happens with each adjustment. You want them to open fairly quickly (1-2 seconds) after reaching 3500-4000rpm, and close fairly quickly (2-3 seconds) after releasing the throttle. You can never obtain a fast/precise operation this way, but it's cheap and a lot better than relying on your exhaust to do the job. IT's also better because you can open them in neutral (as opposed to only under load) and watch what happens for testing/adjustment, and the actuation will be the same in all gears (air pump rpm, not exhaust backpressure).