Sorry for the slow reply, I don't get to check this forum very often (stupid work, grrr)
Anyway, I don't have a real good picture of the installation. The one below is about the best I've got. Beneath that one is a diagram of how to modify the extension. The solenoid is mounted at the top right corner of the picture. The green wire is routed through the framing and still unhooked behind the spare tire. The trunk lock extension needs to be modified to allow it to rotate without the key in the cylinder.
First, remove the latch, and take out the trunk lock. The lock extension is the part that needs to be modified. It is the part that is shaped like a flat head screw, without the threads. Basically, all that needs to be done is to make the slot in the end more of an 'X' shape. The bottom picture describes how it needs to be cut. The best tool to use is a Dremel tool, but a small grinder might work. The X allows the key to still open the lock, but also allows the small release arm to unlock the latch without turning the key. Take off a small amount of material, and then check it with the latch. You want to be able to pull the small arm without having to move the trunk lock. The X should allow it to spin about 90 degrees so the latch releases. If you pull on the arm and it doesn't pop the latch, remove a little more material. If you totally mess up the
extension, they're only about $2 at Mustang vendors.
After its modified, you can reinstall everything. Then mount the solenoid a few inches away on the passenger side, and wire it in to your alarm or push button. After hooking up the release cable, you'll probably have to adjust the length of the cable and the position of the solenoid to get it to release. Adjusting everything to get it to work properly is what took the most time for me.
I love having the trunk hooked up the alarm, its a great modification, and costs less than $15!!