First, connect the FBV via USB to the computer and use the FBV Control software. In the File>Open menu, select the ‘Gearbox’ preset for the FBV. This will store on the FBV automatically. Close FBV Control.
Then, start Gearbox with the FBV still connected to the computer. Go to the Edit>Preferences window, and in the ‘MIDI/Control’ tab, select USB Audio Device for MIDI Input. Hit Apply and then, OK.
The FBV will now control certain parameters of the program including Wah/Volume sweep and toggling. If you would like to change the behavior of the switches, you should than exit Gearbox and go back to FBV Control once again to assign MIDI CC Toggle messages that correspond with what they want to control in the program. You can reference the chart for Gearbox MIDI CC messages starting on page 2.14 of the following Gearbox MIDI CC Reference Guide: