How to add "c" key to xbmcbuntu web interface remote?

I would like to learn how to add a key to the xmbcbuntu web interface remote.

The existing remote has all of the functionality I need with the exception of the pop-up menu produced by the "C" key on the keyboard.

I would love to be able to bring up that menu without having to pull out the keyboard attached to my xbmc every time I need to do something.

Is anyone able to point me in the right direction? Looking at the source for the web-page I assume that I need to update a javascript .js file?