Thanks to "lancaster6" on our forum for this article.  Used with permission.

Here is how he was able to create a new bi-directional control surface.

STEP 1: Use the Forte 4 control surface editor and set up 14 instrument :volume instances. It was confusing because there are 2 midi channel settings and no explanation as to what they are accessing. The 1st I assigned to the channel that the module was using on the instrument (i.e. my M1 in the 1st instrument slot is using midi channel #14) . The 2nd i assigned to #1(my motor 61 master channel is 1). Set the CC channel to 7 (volume).

STEP 2: Open "my control surface definitions" (users/####/appdata/roaming/brainspawn/forte4/ mycontrolsurfacedefinitions.xml) with an xml editor (ed. or "Notepad++"). I carefully made a copy of my definition labelled "motor 61, and pasted it below and renamed it motor 61-2.

 STEP   3: You need to add a line that i couldn't recreate without copy/paste. you can get it from programfiles/brainspawn/forte4/factorycontrolsurfacedefinitions. you need to copy the hasoutput="1" from the Mackie definition, and include the dot before the h!  My keyboard does not have this character so this was my solution.  I pasted that into the header line for motor 6-2.

 STEP   4: Copy all lines below the top line, and paste them under the last line.  Then change the 1st word of every pasted line from "Action" to "Update".  The lines should read something like "Update.Action"..... and so on.

 STEP   5: Save and exit xml editor. open forte and choose motor 61-2 from controller options. choose motor 61 (midi1, not 2) for in and out.