Thanks! Just did this fix
Bought my 1999 XLT on Friday. Sunday night I couldn't get the passenger side door to open. Luckily, my dealer had the latch in stock (but it wasn't $47, more like $75). They stock the passenger side, say it is the only one that fails. I tried like crazy to pop the latch as you described. I could do it on the driver's door but not the passenger side. I ended up just pulling on the end of the cable. Worked like a charm. Since you have to take the cable out anyway, I'd suggest skipping the tool making and all the other stuff. Here's my process.
Get a new cable from your supplier. Also get a plastic door panel rivet.
1. Slide the passenger seat all the way forward and tilt the seatback forward
Working from the back seat:
2. Remove the two screws holding the window latch to the window frame and push it out of the way toward the cener of the window.
3. Starting at the top back corner, remove the window surround by pulling it straight out, popping the clips loose from the door frame.
4. Remove the two screws and one nut holding the lower door trim panel. At the top rear corner of the panel there is a black plastic rivet. Using a small tool like an ice pick, push the center part through the body. It will drop down inside the door and be lost forever. That's why you need to get one when you get the latch. Now you can pull the outer part out from the front. Pull the top of the panel out slightly and lift to remove.
5. Peel the plastic weather seal away around the square hole in the center of the door to get access to the door latch control mechanism.
6. The upper latch cable is attached on the back side of the mechanism in two places, just like the cable that is attached on the front. A groove in the rubber bushing that is attached to the outer cover of the cable slides into a notch in a tab in the steel frame of the mechanism. The threaded rod piece on the end of the cable is captivated in a yellow clip. You can just barely see the release tab looking through the hole in the center of the mechanism. Practice unclipping the yellow cover on the front to see how it works then push straight out on the tab for the upper latch cable. Pull the cable end out of the yellow retainer and pull the bushing out of the slot in the mechanism frame. If it hasn't already unlocked (mine did) pull on the end of the cable to unlatch the top latch.
7. Tie a piece of fishing line or string onto the end of the old cable.
8. Pop the rubber latch cover off of the two black plastic rivets and pull the cover out of the way to get access to the mounting bolts.
9. Remove the three Torx bolts holding the latch and pull the old latch and cable out through the hole in the door.
10. Transfer the fishing line to the end of the new cable and feed the new cable into the door while pulling it into position with the fishing line.
11. Bolt the latch into place and slp the rubber cover back over the rivets.
12. Reaching over the latch mechanism, slide the groove in the boot into the slot in the mechanism frame. Press the cable end into position and then push the yellow cover back over the cable end until it clicks.
This would be a good time to check and make sure everything works like it should.
13. Finally, reverse the procedures in steps 1-5 to put eerything back together, using the new rivet you bought.
Once I gave up on trying to release the latch from the outside, and ignoring the trip to the parts house for a replacement rivet, it took longer to write this up than to do the work.