If I attend an osteopathic medical school can I still participate in a triple board residency program?

Yes. As a D.O. Trainer i can attest that if you have outstanding med school grades (m.D or D.O.)you are able to get into any residency.The problem is we are training more students than available(desirable) post-graduate spots.
Generally yes. Dos have the option to train in do residencies, those accredited by the american osteopathic association (aoa), or in md residencies, those accredited by the accreditation council for graduate medical education (acgme), so in general, yes you can. You should aim to take the usmle instead of the comlex for licensing, however, as most md residencies will want to see usmle scores.
Osteopathic medical . First you need to attend an approved osteopathic medical education program and graduate with a doctor of osteopathy degree. Then you apply for a medicine or surgery residency program through nrmp, of course you will need to pass all three exams to be qualified for a residency program. After you complete 3 years of medical residency, you can apply for fellowship which is usually 3 years for medicin.