The answer to that question is “no”. You can try to size down as much as possible, but the whole process is going to still give you a poorly fitted suit. The best you could hope for is maybe changing the hem on the trousers and maybe the cuffs on the jacket. I would at the very least try to wear your own dress shirt and shoes (the shirt you receive will likely be a poly-blended one and the shoes will be polished leather crap-toes). You could just try renting the jacket and wear your own trousers if the fabrics are close enough in color.
BUT, as stupid as wearing a rental tuxedo is, who cares? It’s not your wedding. You agreed to be an usher for your friend or family member on their special day to celebrate the union of two people crazy enough to give love a honest chance. Just do what will make them happy, let loose and have fun.