Hi,
the video gives you a step by step tutorial how to replace the timing belt at the Audi 100 / A6 (C4) having the V6 engine with 2.6l or 2.8l. This repair requests special tools, but you may find them in the web.
http://www.youtube.com/watch?v=yuHfqt0NBlA
The video has a German soundtrack, but English subtitles are available. If you don't see them by default, watch the video directly at YouTube and press the subtitle button below the frame.
Enjoy it,
Jürgen