I was just looking at these yesterday. It's known that they are based off linux, specifically Gentoo (due to it's ability to specialize your builds and adapt to just about any hardware). It also seems pretty trivial to install a more generic brand of Linux like Ubuntu onto an SD card, and boot off of that. Once you have Ubuntu, downloading dependencies and compiling CGMiner should be pretty straightforward.

The bigger issue seems to be spending $250 on a device to do this. There are other options (including ones that have a screen/keyboard) that can be had for cheaper than $250.