Technically, it cannot be done. I suppose you could call the GM, and talk with them - perhaps they would be willing to charge your credit card now, then reverse the charge when you arrive, then put the room on your gift card...but quite honestly, I wouldn't risk it.

As you are not a Marriott regular, I would also encourage you to re-consider booking a pre-paid rate - if ANYTHING goes wrong, you will be stuck with that charge - when they say no refunds and no changes they mean it! IMO, the rate is not that much better - especially if you try the discount codes at the top of this forum.

Just a thought YMMV.