(This is my modified version--the original is 1 part each of cayenne,
cumin, salt, crushed black pepper.  I think you can see why I've
modified it.)

For Monday's BBQ, I remembered that the particular chipotles I was
working with were really potent, so I used two small ones (tossed
those into a grinder), about 2-1/2-3T cumin seeds (grinder), about 2T
of black peppercorns (grinder), 2T kosher salt (grinder, but mostly
just to help clean it), and about 1-1/2T of chili powder.  Mix it all
up then you just rub it on a steak.  I don't consider it necessary to
completely coat the meat, though you'd get a stronger flavor that way.
 And no additional moisture (like oil, etc) is required to make the
dry rub stick.