I have to agree with 65535 that you'd need to
build an active device to allow this to work. However, it is I am quite sure doable (never tried it of course).
Im sure there are several people on this forum who could make it happen if so motivated. I could prolly do it if I cared to as well (I wouldn't have a use for such, mainly as I don't own my own
headset).
I also seem to remember in the past people asking about injecting audio into clearcom, and also lifting audio from clearcom for computer recording. If you had a
beltpack and
base station to go with your headset the solutions for these two other things could also be brought together as a solution possibly.
Then again a USB skype headset can be got for like $20 (however not as nice as your clearcom headset!).
If I were to do it I'd prolly build a powered box with a
gain pot for the mic and a pot for the volume of the
speaker, a
PTT button (latching) and such. If you wanted to go crazy you could even make it USB (There are a lot of open-source components out there like arduinos and such I'm sure you could find something).
Have fun. If you do decide to try this, let us know what you do,
etc!