I think he'll get 7-8 carries, and I think he'll pleasantly surprise.
I think Martin was a little rusty at the beginning of the season, and I wouldn't be surprised if he was still dealing with that stinger. Leary was pretty obviously injured because he didn't play nearly to the level he was at last year.
With Collins getting up to speed and this OL(Martin) getting some rest, I think they'll play their best game of the year, from which CMike will obviously benefit. Cassel can actually throw an NFL route, and I think we're going to see it early, so the Giants will play somewhat honest from the get go.
How much playing time he gets will depend on his ability to catch the ball and pass protect. The Giants are a team you can kill underneath with RB dump offs, since they play deep to short. I'd normally be glad to hand McFadden's carries to CMike, but McFadden and Randle can both catch, and this is one defense where that attribute can go a long way.
I think he'll end up touching the ball 8 times, around 55 yards from scrimmage. If he can catch, more. This game will be a test for him, and if he can prove himself then we'll ramp up his production for his reunion against the Seahawks.