This may be way outside the area that interests you about the removal of the Germans from Czechoslovakia, but the Czechoslovak section of the European volume of the 1945 Foreign Relations of the United States series has a few documents relating to the American response to the Czechs ejecting Germans into the American-governed zone in Germany after the war. If nothing else, you can see in these documents how contentious the German question became to the Americans, and how determined the Czechoslovaks were to follow through with the ejection.

I'll actually be checking back here myself in any case.