A friend from TrackMania send me this file:
Download file (Excel)here's the tutorial:
1. Open Windows paint
2. Press on: "Farben" then "Pallette Bearbeiten":
3. Press on: "Farben definieren":
4. Then choose your colour with the scala:
5. Paste the numbers in the Excel file:
6. Open TM and tipe the code that is standing in the yellow marked cell:
...and finish
...homie