Here is what I have, an old pair of Philips Cityscape that I decided to finally see if I could repair (they were replaced by Philips ages ago because of bad inline volume control, but decided to hang on to the old pair as a project).
Anyway, after teaching myself to solder (which isn't easy on these headphone cables), I finally got the hang of things. Three attempts later, I figured out things and soldered all the cables to their sibling. It worked, but the plug connection was iffy and would make them cut out if swiveled, they had to be in the right spot (not planning on using these on a device with a mic). I cut the mic cable, and lose the right channel.
Based on what I've seen on the net, they use the mic wire as an fm antenna, so that's why it extends beyond the mic. So the question is, what to do with that mic cable? Combine it on the plug end with the ground from both ends and leave the antenna end blank? Wouldn't that essentially make it a TRS plug in TRRS clothing? Logically that makes sense to me, but figured I would get a second+ opinion before I kill another 5 inches of cable.
Or maybe I should just get a plug and make them have a sort of breakaway detachable cable.