You'll need to use the linux flasher to enable USB host mode... otherwise it's perfectly safe so long as you don't screw up making the USB power injector (which is pretty simple). Just make sure you use a multimeter and make sure there's 5v going into the line. If you're not going above that there's little chance of messing anything up.

As always, do at your own risk (I've never heard of anyone bricking their device because of trying this... and trust me, they'd be here complaining if they did)