Brisket is a piece of meat that requires long slow cooking with smoke to be tender enough to enjoy. We're talking maybe 5-6 hours at 225-250 F.
I can't get my gas grill to go that low. If you prop the lid open to lower the temperature, you lose the smoke.
I'd recommend testing the grill to see how low a temp it will maintain before committing.
As an alternative, you can cook it in the oven and add a little liquid smoke.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan