Transgendered people that are born one gender aren't considered that gender by the specialists in the psychological and medical communities. Not to mention the fact that many trans people tend to take a good deal of insult to the claim. It makes a mockery of an extremely long, costly, and heart-wrenching process of changing that gender identity. To say the VERY least, pronouns and gender associations are changed once someone adopts that gender role. If this hypothetical person is an MTF that likes males, she would be considered a heterosexual female.
Your assertion that "females like dudes" makes several ridiculous assumptions; so much so that I'd consider the possibility that you meant it tongue-in-cheek. First, you're assuming the person in question likes boys in addition to being transgendered. And second, your premise that females like dudes is faulty. Hence, the "L" in LGB.
As STH reiterated, gender identity is independent of sexuality. And by that I mean that although they face unfair criticism from similar places
ultra-conversative whack-jobs and repressed hatemongers, they really don't have any specific connection. Like, you could call it LGBS for lesbian-gay-bisexual-Samoan, or LGBR for lesbian-gay-bisexual-Republicans (well, on the other hand...). I certainly have no MAJOR objection to the combination, but again, the final term is just out of place for someone that's more than a casual observer.
Hope I'm not causing a huge outcry with all this. Like I said, we're all people and individuals, so there's really no sense worrying about arbitrary labels as it is. I was merely thinking out loud.
...Or, that is... thinking and typing those thoughts on the computer, hehe.