Wow, in all my years of working on my cars I've never used or seen that used before....I have seen it in stores but had no idea what its for. Just looking at it and trying to figure out how its used is giving me a headache!!!! LOL
Rotate the BORG till you find which side fits into the ebrake piston in the middle of the back.
Slide your 1/2 socket extention into it then crank it down. This will allow your emergency brake to have some clearance so u can get the rotors and pads on.
Then when its all back together pump your ebrake handle in the car to rotate the piston back into place.
Borg costs about $10 on average and can be picked up at just about any car parts place.
I just replaced the rear pads & rotors on my G6 GT yesterday. I used a 1/2" wrench to turn the brake piston in. Took about a couple minutes to do for each side. I would do a full turn pushing with light pressure, then I waited half a minute, gave it another turn, another half minute and another turn put it all the way back in place.
It's also good practice to pop the hood and remove the brake reservoir cap to relieve any pressure.