I have a 96 xj6. Battery was removed, trunk is closed, and I only have the valet key... How can I get into the trunk to put in the new battery?

 

Hook jumper wires/ to the underhood power point at the firewall and ground, then open it like you did before. If the electric lock is also locked, you can get to the trunk lock rod through the tag mounting hole.
Good luck and tell us how you make out.

 

Hopefully you have better luck than I did with this, as I had to cut open the area around my license plate!

Through the lower license plate holes, you can hook the trunk release and open it up. There may or may not be a plastic guard covering the mechanism. On my car, there was, so I had to shove one screwdriver down, lift up the cover, and insert another screwdriver in the other hole to move the latch. It was quite the headache in a Walmart parking lot, and I had to use sheet metal cutters because I didn't know what the cover was at the time.

Here's a picture of what it looks like inside. Without a cover, you can clearly see that you need to push the silver tab to the right. Good luck!

 

Jesus, thats a savage hole!