I guess the closest you could get to a Tuxedo Siamese would be a Tuxedo Oriental. The Siamese by definition is a pointed cat. The gene is recessive.
I've never seen a bi-colour Oriental, I think a friend told me that somebody is breeding them in Australia, but I'm not sure if that is in fact correct. I'm just looking at one website & it says the Oriental comes in 155 colours.
Also, we don't use the term "Tuxedo" in Australia. Is there actually a difference between a bi-colour & a tuxedo?
I think my cat Eliot would be classified as a Tuxedo.http://www.cat-world.com/~Photos/EliotSept.jpg
PS: Just found this site, which is probably the Australian breeder my friend was referring to. She has some photos of Bi-Colour Orientals here. As you can see, they look like Siamese, but aren't pointed.http://www.geocities.com/catsgalore0..._Orientals.htm