Another possibility is to waive Blair and bring up either Rick Jackson or Jamychal Green from the Toros. Green has been a monster on the boards, grabbing almost 40 total in the last three games alone. Jackson plays under the glass well. Both of these guys are true 6'9". Green appears to have the edge in athleticism among the two, along with being able to hit his free throws.
Concerning Donte Greene, earlier this year I wanted the Spurs to take a look at him, but this late in the season I'm not sure how he would both be able to get into game shape, along with learning enough to fit with the team. He has not played in a game this year to my knowledge.