How do I create submasters for features built into moving fixtures?

Couple things which might help--

The current Eos personality for the chauvet maverick mk II profile appears to contain an error for the Beam FX Index/Speed parameter--it's set for snap, which prevents it from ramping.  Go to patch, click the softkey for Fixtures, select the profile, and clear the checkmark in the Snap column next to Beam FX Index/Speed, then save the changes.

There are also a few ways to get a slider to ramp across a full range from negative to positive values, although they're somewhat kludgy.  

If your sub is set for restore to background (which is the default), the bottom of the slider will be whatever that background value is.  So to get the behavior you want, you could record the rotation speed at full reverse in a cue or in a second sub, then record your working sub with the rotation speed (and nothing else) at full forward.  The slider of the working sub should now give you the full range.

Another fancier way would be to record a special cue list just for this purpose--the first cue would contain only the desired channels and parameters set for full reverse speed, the second cue recorded at full forward speed.  Set the cue list properties as a manual master with back from 1st and go from last set for wrap.  You can also set that cue list's parameter and channel filters to make sure you don't record anything else into it accidentally (or more precisely, if you do it won't play back).  Assign the cue list to a fader and voila.

A third way would be to re-assign the user values in the fixture profile so they aren't negative.  Then you can have 0 be full reverse speed with everything ranging up from there, which would let you use a sub without the requirement for having a background state.

Couple things which might help--

The current Eos personality for the chauvet maverick mk II profile appears to contain an error for the Beam FX Index/Speed parameter--it's set for snap, which prevents it from ramping.  Go to patch, click the softkey for Fixtures, select the profile, and clear the checkmark in the Snap column next to Beam FX Index/Speed, then save the changes.

There are also a few ways to get a slider to ramp across a full range from negative to positive values, although they're somewhat kludgy.  

If your sub is set for restore to background (which is the default), the bottom of the slider will be whatever that background value is.  So to get the behavior you want, you could record the rotation speed at full reverse in a cue or in a second sub, then record your working sub with the rotation speed (and nothing else) at full forward.  The slider of the working sub should now give you the full range.

Another fancier way would be to record a special cue list just for this purpose--the first cue would contain only the desired channels and parameters set for full reverse speed, the second cue recorded at full forward speed.  Set the cue list properties as a manual master with back from 1st and go from last set for wrap.  You can also set that cue list's parameter and channel filters to make sure you don't record anything else into it accidentally (or more precisely, if you do it won't play back).  Assign the cue list to a fader and voila.

A third way would be to re-assign the user values in the fixture profile so they aren't negative.  Then you can have 0 be full reverse speed with everything ranging up from there, which would let you use a sub without the requirement for having a background state.