I figured this out. For anyone looking to do this, it was super easy. Here's what I learned. There are 10 pins, each cut to different lengths.
Step 1. Remove E clip, plastic thingy, and push cylinder out.
Step 2. Remove 10 pins. 5 go in from the top, 5 the bottom. You can see little springs in the tumbler where the "hook" part of the pins go.
Step 3. Install pins one at a time, and insert key. If part of the pin sticks down, you need to try a different pin. What you're going for is when you put the key in, the pins stay flush. I took pics of a properly fitting pin, and a not properly fitting one.
At first, I put the tumbler back in and tried turning. Then I found out about the flushness. Made it much easier. I only was able to get 7 out of the 10 installed and fitting properly, but that's a lot better than the alternative of no trunk lock. There is a little spring and ball bearing that go in there towards the end, but I didn't put mine back in. Hope it wont hurt with it not in there.
Enjoy the pics, and I hope I helped someone.