After reading some articles about Ginther, I think I more or less understand how she did it.
It’s apparently possible, or at least was in Texas at the time, to buy scratchoffs in a way that shifts the odds in your favor such that the expected payout per ticket becomes greater than the cost. The problem is that you have to spend 10s or 100s of thousands of dollars a year on tickets to win big doing this.
Her first win was not a scratchoff, but was one of the pick a series of numbers type games, and this win was almost certainly dumb luck. Because of it she had an annual annuity of $270,000 and spent at least a portion of that according to a system that gamed the way scratchoff lotteries are designed (and pretty much have to be designed) and may have involved a deal with a convenience store owner that allowed her to buy entire packets of certain games when they arrived.
Harper’s article: http://www.toddmeierhans.com/harpersmagazine-2011-08-0083561.pdf
Three part article from the Philadelphia Inquirer: http://www.philly.com/philly/news/lottery/265261001.html