When I ran out while I was on a extended stay in Australia (Adelaide) i went to the local clinic and explained my situation. They contacted my clinic in the US and then they approved me. I was staying with someone so I had an address but I'm not 100% sure how much that mattered.
The problem is, I was on 380mg/day and the clinic said the maximum dose allowable was 180mg. So I dropped my dose by 200mg overnight. As a result, I was sick for the remainder of my time there. But hell, it's a whole different world than going from 380mg to 0mg. Going cold turkey from 380mg of methadone seems potentially fatal
They (the public clinic) did tell me I could potentially find a private pay physician who might be willing to prescribe me more than 180mg, so I drove almost two hours to see this doctor in the middle of nowhere (it was really remote, started getting drier and drier and I thought it was going to turn into Mad Max style desert), only for the guy to reject me (after studying my American methadone pill with a magnifying glass -- all methadone is liquid there apparently?).