TAMMY-
You can have your cake and eat it too.
If the Yorkshire Terrier is truly the breed you love, then you should be able to accept (not necc. agree w/) the opinions of the breeders that have worked so hard before you to provide us w/ the Yorkshire Terrier and what it is today.
If you're wanting to take an "off" colored Yorkie and breed healthy lines that still adhere to the standard of the breed, except in that regard, then you STILL should go to shows and find out what you can about the Yorkshire Terrier as a whole. Develop an eye for faults and proper markings and coat texture so you will then know what you are producing to be of quality in regards to the standard.
I still think that you're talking semantics when it comes to the Biewer and the Parti. Take a look at both closely. I'd attend Biewer shows if you can and do the same there that you would at any AKC show w/ the Yorkies. It will do nothing but better you as a person in regards to the breed and therefore make you a better and simly more knowledgeable breeder.
It IS true that you'll have to hold your tongue in regards to some of your desires in where you want to go w/ the Yorkshire Terrier if you're wanting to breed Parti's, but even still, I think you'd only be detrimenting yourself and the breed if you didn't still take these steps to learn about the breed and just why it is that so many breeders out there aren't in line w/ you on this one.
I'd go to the shows, soak up what you can, take that home for the day and sleep on it. Who knows, your opinions might get stronger and then again, they may waiver.
Either way, it's great that you have a dream! Keep your chin up and ears open and you'll get there!