Elliot
I am overseas and buy RE from here. As to the "how" -- you need people in your target area who are aware of your situation and willing to accommodate never being there in person. For me, this has meant a realtor and mortgage broker. Yes, I may pay more to use the broker, but they streamline the coordination. It's the price I pay to do this all remotely. I use my brother as my eyes and ears; we partner up in the sense that I am the financial backing and he does some of the legwork. He does not sign anything and I don't bother trying to use a power of attorney due to the hit and miss results in terms of who will recognize and accept it.
The only time you need to return original, signed docs is for the closing. I print the closing package then use the notary service at a US Embassy / Consulate or if you're associated with the military in any way they will have somebody who is a notary which is also acceptable. I then FedEx the paperwork back to the US for the seller to sign.
I have never sold RE from overseas.
Tim