We have had clients who have committed the crime of DUII in Oregon and have done their treatment in other States. Doing so requires special arrangements. Your son should consult an attorney who handles representation of clients in DUII matters, first to determine whether there is a possible defense in his case, and second to get help in navigating through a legal system that can be very confusing and daunting for the non-expert. Feel free to contact our office for further information.
The only thing I can add to Mr. Cogan's answer is that your question involves application of the Interstate Compact for Adult Offender Supervision, and you'll want a qualified and smart DUII lawyer for your son to consider both that law AND all the (probably more important) issues brought up by Mr. Cogan in his post above.