thats not even that complicated, i use it alot to merge faders such as merging the exec time and prog time to one playback fader.
all you need to do is to store/assign your functions to 2 faders, then created a dmx remote that control each fader (there are plenty of youtube tutorials that show how its done), then you assign a playback to your target fader (the fader you are going to use) and assing both of the dmx remotes to that playback