After several hours (days?) of work I finally got my own TinyTrack running. Currently it is planted in my car and connected to my FT-5200 and an Etrex GPS receiver. When I have some more time, maybe after the A-Level exams, I’ll install a KF-163 or something in my car.
Howto build a TinyTrak: www.dk7in.de

Update 24.Sep. 2006
The TinyTrak does its work very reliable in my car for months now. As you can see in the images it got boxed together with an old handheld transceiver and a thick battery to supply power when using it stand-alone.