I had a friend do one adapter for me, basically we assumed that the "base" connector was the ground, and the tip and the middle one were for microphone and mini-speaker, we did not knew which. So he made a Y connector like this:
[||stereo 2.5 mm mother jack]]-----(wire from tip)---...-----[[stereo 3.5 mm jack]==>
\----(wire from middle)--...------[[stereo 3.5 mm jack]==>
the stereo conectors entering the computer (3.5 mm) were made "stereo" by soldering the both channel togheter.
And we plug them at chance, when I don't have sound in the headset, I revers the plugging in the computer. It works perfect with Skype.
It might sound dangerous to plug them in reverse, but I doubt that the condenser microphone can be damaged by the low voltage of headphones out from the computer.
Laurian
[BeoMaster 1900, CD 50, Beovox S25 S35 S50, BeoSound 2, BeoVision MX 1500, Form 2, LC 2, A8, A9]