Thought I was being brilliant, but discovered searching here that someone else did it first, so here's their link:
creating a programmable remote shutter release for Pentax Kx scanar
Didn't want to hassle with 2 remotes and a floppy plug, so I bought the larger intervalometer
Ordered from China one somewhat inexpensive Pentax intervalometer ($35) and one inexpensive Pentax (K-x) infrared remote($5).
Despite not having a non-K-x Pentax camera, I didn't want to lose the wired functionality of the remote (figure I paid for it), but I didn't want to be carrying around a floppy bundle of wires that I wasn't using either. Decided to get a 2.5mm stereo jack from radio shack and wire it inline, so that a male/male cable could be used with a wired camera at some point in the future.
By chopping off the back half of the infrared remote, it will fit in the cavity of the intervalometer. Because the switch is on the right and the intervalometer board interferes to the front, the LED has to be oriented out the left hand side. This is actually quite convenient, as it should allow the unit to be mounted to the side of the camera strap bracket with the LED pointing directly at the IR sensor. Naturally you need to make a LED sized hole in the side with your hole making tool of choice.
Having removed the battery section of the IR remote, the IR board can be wired to the intervalometer battery contacts. The contacts are just kind of sitting in indentations on the board, so they will come loose when adding the wire if you are not careful.
The RED and Blue wires from the intervalometer can be wired, one to each side of the switch junction on the reverse of the IR board. Because this side is facing the rear of the intervalometer PCB, it would be a good idea to cover the contacts with liquid electrical tape or similar when you are done.
**Note: The pictures show the blue and white wires - THIS IS WRONG - Blue and white have continuity as long as there is a battery in the unit, even when the power switch is off. The blue and red wires should be used instead.** I fixed this, but was too lazy to take more pictures.
If you want to retain wired functionality, wire the stereo jack inline. White is ground, red left channel, blue is the right channel... Of course, you're checking continuity to verify this, right?
Left the stub of the cable in the front just to keep dirt out.
The piezeo got knocked off by accident during final assembly, and I decided I was done with soldering for the day and didn't mind not having beeps, but it will fit in there too. Those foam double sided sticky squares used to hang posters work great for holding the piezo and the IR board in place.