Simply put, this is easiest with two controllers. Start up a game of 8 ball. Put the gamertag you want to get the achievement on the second controller, and a useless gamertag on the first controller. The first controller will shoot first. I simply aimed at where it was already aiming and shot with the power it gives you. Most likely you will sink a ball. If not, restart. Choose solids/stripes if it prompts you (it really doesn't matter unless you can't pocket the 8 ball right away and want to set up a shot - you'll have to sink another ball to get another turn, and in that case you'll want to pick an easy shot / shot that sets you up, where stripes/solids could matter). Pocket the 8 ball with that first controller. Therefore the second controller - your profile - never lost a turn since he never shot, and the achievement should pop.
If you don't pocket a ball on the first shot, don't sink the 8 ball before the 2nd player's turn, or just hate the setup you're given, simply hit start and quit, and set it up again. I probably set up 15 different games or so to get 5 games where something didn't go wrong. Took roughly 20 minutes.