instead of hooking up pots to the AIN module, put there jack sockets and plug it into and audio signal as a CV (Controll Voltage) then if you have a VCF (Voltage Controlled Filter) on your PC, it can be controlled by midibox’s normal midi output. maybe expanding that idea would create something usefull.
The MIDIbox Extensions page http://www.ucapps.de/midibox_ext.html shows some examples for CV Inputs, e.g. a Breathcontroller and an analoque LFO. Of course, the possibilities are endless, it’s your turn to realize and documentate your ideas