Help!

I've searched through the discussions regarding makeshift car kit options. I'm able to use my cassette adapter with the HS stereo adapter so I could hear MP3 music and phone calls using my car stereo.

I'd like to be able to use my 2.5mm microphone I had from a previous cell phone. Does anybody know if there is an adapter to separate the mic and stereo outputs from T600's 2.5mm jack? That way I can use both the mic and my car speakers.

Thanks!