The tally on the left in the linked document estimates the remaining states based on polls/the results of similar states. In this scenario, Romney ends up with 1,117 delegates, with 319 unbound and RNC delegates. Romney won 3 of the 6 states that don't allocate their delegates at the caucus an has thus far won 86% of the RNC delegates that have committed. So he'd only need 8% of them.
If he were to win 36% of them, he could end with 1,017. In the chart on the right, he'd get 1,144 with that. That chart allocates the unbound delegates based on the caucus vote results.
We should keep in mind that unbound delegates in 2008 committed to John McCain, even if he didn't win the state. It's likely that the powers that be will push unbound/uncommitted delegates to Romney, just as the Democratic powers did with Obama in 2008.