Hello Stefan,
There is a option to at this future to a fader...
The only way is to edit your fixture-personality !
You can at a "custom" color/gobo option to your fixture, a "custom" option is also depend from the fader-position.
I did try this with a High End "studio spot 250" and it works OK.
The option is also to keep the normal "gobo" and/or "color" editors as normal.
The fixture will react on the last action.
If you need a help to edit your fixture-personality... please let me now which fixture you are using.
The fader-mapping is depend about your fixture...
If the fixture has 10 colors, the fader-mapping will give each 10% a different color.
If the fixture gets 20 colors, then it's 5% etc.....
Edit:
After you at this future to your fixtures...
You can start to program some cuelists.
In each cuelist you can at a single fixture ore a group...
If you like to at more fixtures together, just select the fixtures you need...
Here a example to make a "GOBO" fader:
After selecting the fixtures...
Set the "custom" gobo value to 100% and record this to the fader you like to use for this function...
Then activate in this cuelist the "background" option, to set this cuelist automatically active by start.
Set the fade in/out times from this cuelist to zero...
Give the cuelist a name and you are done for this "GOBO" fader
If you now move the fader, the fixture(s) will move the gobo-wheel.
Please notice that if you like to programming with the gobo/color faders....
You only can record it as a STACK !
Also notice that if you have programmed more cuelists including the gobo...
It's possible that the gobo-wheel will not listen to your gobo-fader !
You have to find your own way to use it together with your setup/show.
Here a short video to show how it looks:
http://flic.kr/p/92mubf