We've had this discussion before and the general rule of thumb is that, given the actual population of DOs in comparison to all American medical students, a program would need to have 10-20% of each residency class be DO, all things being equal. Of course, this isn't realistic. ACGME program directors should be looking for the best applicants for their program, regardless of the degree obtained. That's going to mean that some years a DO won't make the cut. Additionally, and I think many people on the DO side understand this, ACGME program directors probably feel some obligation to take care of their own. After all, there are roughly 120 allopathic schools pumping out many thousands of new graduates every year. They need to go somewhere and certainly, given the recent AOA-AGCME issues, they can't go to osteopathic residencies.
With that being said, I think most DO-applicants would love to have a list of EM residencies that are not DO friendly. I can think of a few really good ACGME programs that are DO friendly and have a history of taking 1-2 DOs in every/every other class. Some of these programs are routinely listed among the very top notch and, in my opinion, this demonstrates a desire to recruit the best physicians regardless of background, period. As a DO, these are the places you want to be. I should add that places like Denver Health have taken DO students, again, demonstrating their desire to find the best applicants, regardless of where they went to school. I think any list would have to be separated by those places that are not interested in a DO under any circumstances (based on user feedback and historical data) and those that are open to one but have not yet found a good match, which is admittedly possible.
LOL... sorry, had to do it. I'm sure if you ask you will get the standard "We are open to applicants from all whatever whatever" just like you would if you asked any of the Harvard affiliates, Denver, Vanderbilt, and a number of the Cali programs. Problem is that when you look at their past classes you see absolutely ZERO residents in history were DOs. Short (honest) answer... no, they will not take a DO as a resident. Elective... probably. Someone will undoubtedly debate me and give the "there has to be a first... " argument but when it comes down to it they are right... there does have to be a first... someday. What it will take for that to happen is likely administration change, culture change, and time. 
