I have been researching EM residencies in the southwest. Here are my impressions:
--There are very few. As far as I know, the complete list is:
? U of New Mexico
? U of Arizona
? Maricopa Medical Center (Phoenix)
? a few more if you count Texas (which I would) and southern California (which I wouldn't)
--Of the 3 programs above, UNM seems to be the most competitive, with most of their residents coming from well-ranked US MD schools. UAZ is next, with most residents coming from decent US MD schools. Maricopa in Phoenix is a bit less academic and has, in their current PGY I class, two DO's and even an IMG (from Ross, of all places).
All 3 of these are 3 year programs.
As for Internal Medicine, there are more options, including one sponsored by the Mayo clinic. I don't think any of them are out of the reach of a DO graduate.
Hope that helps.