Oh, Jeff? Your diagram is completely incorrect, I expect more of someone who has p28.pdf.
Sorry, I had 5 mins to create, upload, and post all that. Also, I've never even taken an electronics class in my life. It's more than just a quick glance at a PDF diagram for me, especially with ADD and no meds.
Now that I've looked at that blotchy shit for a while, I can't see how I'm completely off. IC U7 grounds the base of pnp transisotrs #6-9 for injectors 1-4 respectively through pins 22-25, which then lights each collector with an unknown voltage (unlabeled triagle!). Each collector connects to the resistor matrix (RM5's 5,3,7,9 for 1-4 inj) which I guess limits current, which then connects RM5's 4,2,6,8 to QM1/QM2's 2,7 legs, which are the gates for each n-channel MOSFET. Voltage to the gates is regulated by what looks like a zener diode symbol (1 per gate). That allows the mosfets' grounded source to connect the injectors to ground, which are connected to each mosfet's drain. The only big mystery to me is what that center mosfet does for QM1/QM2.
So this is what I see:
For a connection at the logic level with a ground signal as output, you'd connect U7's 22-25 pins to that driver.
For a higher voltage output, you connect the driver inputs to RM5's legs 5,3,7,9.
For a lower voltage output, you connect the driver inputs to RM5's legs 4,2,6,8 and let the mosfet's internal zener diodes regulate voltage to whatever.
I don't know enough about all this shit to really know why you can't use the same signal the MOSFETs' gates use, let alone why you'd have to remove the mosfets. It's assumed the mosfets' drains will not be connected to the injectors, and I can't find anything that says they will blow up with a grounded source, powered gate, and unconnected drain. All I can figure is that you'd bypass the resistor matrix and add your own zener diodes to set the proper voltage.
PS: after looking at the pdf's first page again, I noticed that the "unlabeled triagle" is +5vdc. So then why the fuck can't those +5v signals be used for the jbperf driver inputs?
That's all I can do for tonight, I've have a bad cold since Saturday and I'm fucking tired.