Unexpected Transit

My family and I are flying to Cambodia by way of Kunming. The airline has suddenly cancelled our original flight and now all of a sudden we are being forced to endure a 67 hour layover in Kunming. My wife has a Cambodian passport which is not listed in the visa free transit countries.

Is it possible to get an entry permit on arrival for her since our flight leaves in only a few days? Or do we need to scramble to get one from an embassy somewhere?