Most guides on genetics are going to focus on single-gene mutations like Amel and Anery. Here's one of the best ones I know for that:
http://cornguide.com/geneticspages.php
BUT...Okeetee and Miami are line-bred traits, polygenetic in nature, which means their appearance is controlled by several genes acting in concert. Typically a paint analogy works reasonably well for line-bred traits. If you mix orange (background color of typical Okeetees) and grey (the defining characteristic of Miami-phase), what color do you get? On average, kind of a muddy tan.
Eh. Selecting the holdbacks with the palest background color and the thickest borders will, after several generations, likely yield some decent Miami Okeetees. Unless you begin with fairly exceptional animals, it could take a very long time to produce high quality offspring.