I don't live in OR so I can't say for certain, but OR removed barriers to trans health care in insurance in Jan 2013, so it seems likely that you could get coverage from CareOregon, though you may need to prove "medical necessity" and may even need to take it to an appeal.
Check this FAQ for details.
Additionally, you may be required to use a surgeon in-state. Check out Dr. Juliana Hansen in Portland.
Hope this helps!
When you find out more details, could you please post them here for others to benefit from?