Altitude colors

I want to make a custom altitude color scheme for a map in Ft3. Is there an easier way to do this besides pointing and clicking on the altitude color bar? Toward this end I've also looked at the .lgt files and have a question about them. In the Altcolor section of the file in say the TOPO 50 file in Terraformer there are 21 color levels. I assume the first one is the sea level color and then the 20 represent divisions equal to the max altitude of the map divided by 20?
Comments
Ok, I ended up doing it using Wilbur to modify the TOPO 50 file and then saved as my worldname.lgt.
That's how I did it when I wrote The One Day Wordlbuilder, but I'm sure there are better ways even than that.