you did not read this...buy a 4 pin molex to 6 pin cable from micro center...that if you mb has another video card slot.
bad side is if there running any keystoke program or look at the hardd drive after you leave there going to be game files still left on the work pc. also if it a good size company the have ip sniffer programs go to the wrong web page and a warning might pop up and to pc mac addy might be logged. if dont want to buy a cable..you can green wire a ps on..you use tech use this for test benches and ps test where you get those mb failures when system has no power but you want to know if it the mb or ps. so you green wire a ps and check the voltages.
You can probably steal a molex connector from a CD/DVD drive. Every PSU I've ever seen has 4 pin molex cables.
So, barring some better solution, you could install your games via CD/DVD (if necessary), power off the computer, steal the molex cable from the DVD drive and convert it to 6 pin PCIe for your video card and be good to go.