In xLights, create a "Channel Block" prop, 1 channel, likely "white" color for the channel although it doesn't really matter. You can then add that prop to your timeline.
To sequence things, drop the DMX effect on it. You can then assign raw DMX values at any given frame.
You could also create "States" in the Channel Block model that map various stated names to "colors" (shades of gray) and then use the "State" effect to select the appropriate state at any given time.
In FPP, you would then setup the events. This is described fairly well in the manual:
https://falconchristmas.github.io/FPP_Manual(4.6).pdf
on page 65. THAT said, much of this is changing (will be a lot easier) in FPP 5.