You don't need anything specific. You just have to apply for the Vietnam Citizenship in their embassy and then you need to fill the necessary documents. Then you can live in Vietnam.
I Want To Live In Vietnam With My Wife Permanently....how Would I Go About Doing That? I Am An American Citizen By The Way.
If you are vietnamse, you can come back vietnam as a vietnamses but if not You can not get citizen in vietnam as a vietnamse because in vietnam the wife will follow husband,not husband have to follow wife.