Go to page 8 on this. http://www.msdignition.com/pdf/7 series/7230_7al3.pdf Where the shift light is connected you will wire that the positive side of a 12vdc relay coil. You need to wire your electric shifter to the NC or NO side of the relay depending on what shifter you are using and supply the common side of the relay with a fused + 12vdc source.
What type of solenoid? Is it spring loaded and fires when power is removed or does it fire when energized? If it is the second type, run a jumper wire from "IGN" terminal to "RAS ON/OFF" terminal. Run another wire from "IGN" terminal to terminal 86 on your relay. Run a wire from "OUTPUT RAS" terminal to terminal 85 on your relay. Run a 12V source from battery to terminal 30 on your relay and a wire from terminal 87 to your shifter solenoid.