i did not necessarily come out and say, "i want to be a DO," but i did use a lot of the osteopathic catch phrases in my personal statement (i.e. "holistic", "like using my hands", "patient centered", "treating the person not the symptoms"). surprisingly, i received interviews/acceptances to MD schools as well.
...now that i think of it, i wonder how much time admissions committees put into reading those things...hm.