I also love Dewey's pizza - one of my favorites in the Dayton, OH area.
In May, 2012 I took a pizza-making class "Dewey's Pizza... and More!", taught by Chuck Lipp (Chief Operating Officer and Partner of Dewey's Pizza, responsible for menus and develops the recipes for Dewey's).
I asked a few questions and got the scoop on some of the ingredients used by Dewey's...
First the sauce: The base is Stanislaus Pizzaiolo, with added salt, red pepper flakes, spices and garlic salt (no further info on proportions, or which "spices").
Their cheese is a part-skim mozzarella from Burnett Dairy. (He said it was called "Patria", but I can find no info on the web except that Burnett is a Wisconsin dairy cooperative.)
Their pepperoni is from Ezzo Italian Meats in Columbus, OH. (I believe it is their GiAntonio "Old World" type, which has a fibrous rather than a collagen casing, so it doesn't curl or char.)
Anyway, some info "from the horse's mouth"!
The sauce shouldn't be too hard to "clone" with some experimentation, because Pizzaiolo sauce is fairly easy to find, although only in #10 cans.
The Burnett cheese is probably impossible to find (possibly custom-made for Dewey's?), and even if you could find it you'd probably have to buy 50 pounds...
Dewey's, like most large operations, can get KILLER ingredients like Ezzo pepperoni and Burnett and Grande cheeses that simply aren't available to non-commercial buyers or in reasonable quantities.