I bought one that looks exactly like this, I don't have the exact link but this is the same thing. You have to plug in the USB to a wall charger or PC USB port, and you need to be on a stock rom because slimport doesn't work with any of the CM or AOSP based roms I tried.
Using this cable, the G2 actually outputs a pretty good video feed at 1080P. The colors look a bit washed out on my PC monitor but the speed is good and games can run at around 40+ FPS (as opposed to 60 FPS when not using slimport and just running on the phone). I also use the Moga Pro controller, it's Bluetooth and has very little input lag, I don't have a PS3 controller.
I just wish CM would fix slimport, it is a huge feature for me.