I got into CCOM with an MD letter and 1 hour of DO shadowing.. Really, it doesnt matter because most DO's practice exactly like MDs do. so, why would it make a difference if you shadow a DO or get a letter from one? During my interview at CCOM, I had 2 MDs and a PhD interviewing me. I had written in my personal statement that I wanted to "treat the whole patient". The interviewers actually challenged me and asked why MD's cant treat the whole patient. It kind of caught me off guard.
Just make sure you know what osteopathy is about and what OMT is and dont be cliché about it.. e.g. "I want to treat the whole patient" - everyone says that. Be sincere about your interest in medicine, and include that you would like to explore manipulation as an alternative treatment. In reality, there are a large number of patients that are out there with back pain and muscle pain that cant be treated effectively with current medications. In some cases, manipulation can really help these people...