Repurposing an EQD Hummingbird for Control Voltage output

[negativefx]

Hi all,

I just picked up a WMD Geiger Counter and I'm interested in hacking up my EQD Hummingbird to output control voltage to the CV In on the Geiger Counter.  Basically just use the helicopter/machinegun chops of the Hummingbird to control the GC.  The GC accepts 0V to 5V for it's input.  Any ideas where to start?  

Path: Guitar to GC in, GC out to amp, Hummingbird Out to CV In, nothing into Hummingbird In

You can just a plain old expression pedal to CV In... I'd like to replace it with the Hummingbird.

Thanks!