Pocket PC in the cockpit question

I've tried googling for answers, but have come up short. I am the proud new
owner of a Dell Axim X50V handheld PC that I intend to use for instructing.
In addition to keeping track of my schedule, contacts, and location via a
bluetooth GPS, I'm interested in using it as an inflight recorder.

I've found plenty of information regarding attenuated patch cables, but I
can't seem to find the appropriate connector to use with the Axim. It has a
four conductor 3.5mm audio jack that is used for both stereo headphones and
a microphone. Unfortunately, no one makes a headset that uses this
connector, nor do they make an adapter that spits the 3.5mm four conductor
plug into a 3.5mm mini stereo audio jack and a 3.5mm mono microphone jack.

Ideally, what I'd like to fashion is a two way line from the handheld that
could plug into a spare intercom headset jack combo. So the audio out from
the Handheld could be piped into the mike input on the intercom, and the
output from intercom audio (what would otherwise go to the headset) would be
be channeled (and attenuated) into the mike input of the four conductor
handheld plug.

The advantage of going both ways is that I can both record on the handheld,
and listen to the handheld (audio checklists, recording playback, reminders,
alerts, etc.)

Has anyone done this? Any advice or schematics? I'm willing to get out the
soldering iron and make something up, but I'm not sure I know which parts to
use.

Brad