There's already a hole with a rubber grommet for the AUX cable in the pocket, you could remove the 4 pins that hold the pocket in, push the AUX plug out of the hole, hook your audio extender to the AUX plug and wrap up the excess under the cubby and run your usb plug out the existing hole to your handlebars and the other end to USB power in cubby(plugged into 12V receptacle).
You'd have to remove the pocket but it's not that hard. You'll also need to remove the trim strip that covers the outside edge of the cubby.