The clothespin and hangar idea did not work in my setup. I wound up just standing the graters on their narrow end and leaning the plastic top-handle against my leg. Then I had to keep myself from jumping when the 5 minute timer went off, lol.
I'll think of something though, and will post when i figure it out.
I would like to find something more substantial (and most importantly, cleanable) than the cheese graters, like a S/S hinge I can take apart, or a couple of S/S discs or S/S tiles even.