Here's the site I found: http://www.exatorq.com/ludis_obd1/spit.html

It has various EPROM images for dumping the ROM. You're right; it doesn't use the standard ALDL pin.

Ground ECM pins A12 & D1. Connect a 12 volt power source to ECM pins A6, B1 & C16. Connect the positive end of a 1 µF capacitor to ECM pin C6. Note, this is not the regular ALDL output pin. Connect the negative end of the capacitor to your computer's RxD serial port input. (Also provide a ground connection between the ECM and serial port.) On the computer, run a terminal emulator set to 8-N-2 and 9600 baud. The ROM contents should now be dumped repeatedly to your terminal in Motorola S19 format.