First, select any of the Las Vegas Events. After choosing, begin the tournament.
Try to only play hands that you have a shot at winning (use the different screens that come up when you hit "RT" in order to help with your decision to fold or stay). Every time you win a big hand, hit "start." This will save your progress. If you ever lose a big hand, quit to the dashboard and reload your last save.
Continue this until you reach the "Final Table" of the tournament (this is where there are only 9 people are left in the tournament). Now you can either lose on purpose to get the achievement or try to win in order to get the achievement for winning the event.