Sure!
Add a compressor block immediately after your IN 1 block. Select 'Optical Sustainer' from the drop-down compressor type menu. (I typically select Studio FF Compressor for Channel A, and Optical Sustainer for Channel B.)
In Optical Sustainer, right-click the Sustain knob in order to open a modifier screen. Select your Source as a Control Switch (CS 1 is OK). Set your attack at 200 ms, and your release at 800 ms. Exit the modifier screen.
(Be sure you have a free footswitch available with which to include this next step.)
Within FM9-Edit, enter FC Per-Preset. Select one of your pre-presets to be the same control switch you selected in optical sustainer modifier. Select under Tap: Category: Control Switch, Function: Momentary, Control Switch: CS(1-6). Select a name for your per-preset. (I prefer Custom > FEEDBACK.). Remember the Per-Preset # associated with the Control Switch. Exit FC Per-Preset.
In FC Edit, within one of your layouts (I prefer Scenes, because it is readily available there instead of placing it in Presets or Effects layouts), choose one footswitch that will be dedicated for per preset control switches.
Recalling the per-preset # you had chosen for CS, under the dedicated footswitch, select Tap, and select Per Preset from the drop-down menu. Be sure that number corresponds to the per preset you had selected within FC Per-Preset.
To the right side of FC-Edit, under Per-Preset Override, select from the drop down menu the same per-preset number value you selected within FC Per Preset for momentary Control Switch. IIRC, a screen warning will pop up asking "Are you sure?" Click OK to complete.
If you've done the previous correctly, your Scenes layout should contain a Control Switch footswitch that will work for that preset only. If you need to repeat the process, it will be necessary to go back and repeat the build process for each preset that you want to contain an optical sustainer control switch modifier.
The alternative, although I've not tried this myself, is to simply add an optical sustainer, and not add the dedicated footswitch, control switch modifier, nor per preset. The optical sustainer will work on its own, but won't have the same attack/release qualities associated with the control switch modifier. IMHO, the control switch modifier sounds more natural, and rises and decays with harmonic overtones "better" than the optical sustainer itself.