Well, Aali's driver already does the much prettier SSAA inherently (just set the internal resolution extremely high). Beyond that, most of the game is 2D assets anyway, and fairly simple 3D. I'm not sure how much it would have to gain.
edit: Hmm. I thought sure his driver let you manually set the internal resolution, but all I see in the cfg is window_size_x and window_size_y. Nevermind, then. Unless there's some hidden setting that isn't in the cfg by default.
edit 2: Try internal_size_x and internal_size_y. I see them mixed in with the other options in ff7_opengl.cfg, so there's a decent chance they can be set.