[AT&T, Rogers HTC One X, Telstra One XL] iElvis:
IMPORTANT UPDATE: After a month of running this, I have concluded that the Palm components are not compatible with this phone. I was getting frequent reboots and eventually some instability of my phone. A couple of times my phone went temporarily dead and would not revive until I plugged it into the wall. I'm leaving this up in case others want to try it, but be aware you may be asking for trouble.

Lots of people have hacked the Palm Touchstone inductive charging setup for their phones, but I've seen nothing specific for the One XL. I used this thread by android94301 to get started. It's good for background and applies for the One X up until he starts putting it in the SIII back. Go and read the OP, as I won't repeat much of it.

I used the charging case approach because I did not want to open up my phone or make any permanent modifications to it. I wanted something simple, removable, and non-destructive. I used a TPU case because a) it's flexible enough to accomodate the charging coil and b) it's what I had. Plenty of other cases ought to work.

I would not advise attempting this project unless you're pretty handy with a soldering iron. You have to solder all the parts together or your won't get a good connection, and it's hard enough even then.

The Touchstone base will not work with a phone charging cord or the USB port in your computer because it needs more than 0.5A. It will, however, work with a tablet charger--at least it worked with my Nexus 7 charger--so if you've got a spare, you can save a few bucks and use that.

What you'll need:

-a charging back from a Pre or Pixi--I used the Pixi; be aware the Pre coil has the polarity reversed.

-a soldering iron

-some thin wire. I used two different colors to keep the polarity straight.

-some method of keeping the leads in contact with the pogo connectors.

-a multimeter to check your work. You'll want to repeatedly check whether you're getting 5V from the charging coil, because it needs to be aligned correctly with the base.

-a utility knife, wire cutters, and small needle nosed pliers

1. Start by carefully removing the coil assembly from the back. Peel the tape off, and keep the silver tape--you'll need it later. Using a sharp knife, very carefully pry the coil up from the adhesive. Pry out the four metal discs (be careful here--the Pixi back is quite flimsy, and I ended up punching the precision screwdriver I was using through the back and into my finger).

2. Once you've got everything free, place the case on the base and arrange the coil and discs so everything is in position. Check voltage with your multimeter. (Note: I ended up reversing the arrangement of the coil in the final version--it doesn't make a difference which way it goes.)

3. On the copper tape attached to the coil, you'll see two square contacts. Solder a wire to each one. On the Pixi, the contact at the end is + and the other one is -. Note that in this photo, red is + and black is -.

4. This should take you 10 minutes, tops. Now comes the tough part. By far the hardest part of this hack was getting a good connection with the pogo contacts. I came up with a workable approach, but you may want to try something else. Whatever it is, it needs to keep pressure on the leads to keep them in contact. Simply taping the leads to the contacts does not work, however.

What you see here is a piece of circuit board cut from an old 2.5" SATA hard drive adapter. I used it to fabricate a little pogo pin board by removing all but two of the connecters with my soldering iron. I pushed the remaining two through the board a bit further after melting the solder, then soldered the leads to the pins. You may note that the wires are reversed from the previous photo--this is because I accidentally soldered them in the wrong arrangement on the board, and immediately after this realization, the black wire broke off the coil. So I just unsoldered the red one and reattached them so the board would get the correct polarity. Again, check your work throughout this process to be sure you're getting a charge at the final connection.

5. Tape or hot glue everything into place. I taped my pogo board directly onto my phone just to make it easier.

This isn't quite the final product. I'm going to move it to an opaque case, and I'm going to try shaving down the pins on the pogo board because it's a bit thicker than I'd like. Still, it all works.