Sorry to bump an old thread, just wanted to give some input on the topic.
I've used ATI tray tools way before I learned about mining to overclock the 6750M in my MacBook Pro for games and it worked pretty well. I've managed to get the perfect amount of core overclock, memory underclock, undervoltage, <85C while getting ~95MH/s. With my gaming overclock profile it mines at ~100MH/s but the temps go over 100. I know the hash rate isn't high for today's standards but I thought it was impressive coming out of a pretty old graphics card.