A super mojave also known as a Blue eyed Lucy are not totaly white. They tend to be very dirty looking:

I found this link doing a search on a super mojave:
http://www.boaconstrictor.com/index.php?productID=136

You can also breed a lesser to a mojave which 25% would toss you a white snake, a white snake from this breeding would be cleaned up better.

Lesser x Lesser = an even whiter snake (again if you hit that 25% mark)

Also lesser x phantom = gives you a whiter snake, Ralphs "Karma" is one such example