As a former EMT, dispatcher, etc., I must say that if you cannot get out of the way of an oncoming emergency vehicle (in our case, an ambulance),
don't farking try. If there's a curb on one side that you can't get any closer to, that's fine. We'll go around you.
Don't bother with pulling into shoulders and whatnot -- we frequently use those to pass in an emergency. People pulling into them simply block that route for us.
Now, if you have the opportunity to safely pull to the right of an emergency vehicle, please do so. Use your turn signal so we know what you're doing. Funny story: While on a Code 3 call in San Jose, California in a primarially Vietnamese part of town, we came up upon a small car. Evidently the driver panicked upon seeing the ambulance behind him, and did nothing. "Fine", we said, and attempted to pass him on the left. Amazingly enough, he must have decided "I must get out of the way!" and went to the left, blocking us. We attempted to go back to the right, and he did too, again blocking us.
By this time, we could tell that he was extremely agitated (his arms were flapping and the car was weaving back and forth in his lane), so we backed off, moved several lanes over, and passed him safely. One wonders he was FOB and unfamiliar with American ambulances?
I think that Public Safety officials in various states should get together, come up with a unified plan ("pull to the right if possible, otherwise stay in your lane") and put out Public Service Announcements to that effect. It would reduce much confusion and problems involving emergency vehicles.