ok, i guess it's time i jump-in here. whay kind of budget are we woking with , here? i know someone with the injectors you need. unfortunately, they won't be free. they won't be huge money (i don't think) but definately not free.
with the pressure switch, i don't know that it'll be 'fast' enough to help with a high boost condition. you'll also need something to drive or cycle the injector. i think you should be careful with ghetto-rigging a Toyota...there are better ways. 'cause if you screw it up, it's a bitch to fix. i wonder if the 'old school' tricks that TRD/TTE used to use on the 3SGT-E and 4AG-E would work for you...