Every year it seems like some ACGME program that hasn't taken a DO in the past takes one. No ACGME program takes them regularly...there are enough competitive applicants on the MD side that they dont NEED anymore. Your best bet is usually the lower/middle tier programs or programs in less desirable locations. When scheduling away rotations, dont be afraid to ask the PD if they would consider a DO or if they have taken one in the past, you can gauge where they stand.
Just because a program has a DO in the program now doesnt mean they will take another. One thing is for sure, you would need to rotate at the place and/or have some kind of personal relationship, best achieved through research.
Do as many away rotations as you can to increase your chances. Most applicants on the MD side will only do a couple.
PM me if you have specific q's. I'm a DO at an ACGME program.