Getting a geopolitical arrangement set up where Central Europe is one big demilitarized neutral buffer would be helpful.
Stalin Note Germany, Neutral Czechoslovakia, Finland, and Yugoslavia together could be a buffer between the alliances preventing broader conflict.
Plus, given how much of the Cold War was straight geopolitics between two global powers, I think you'd need alternative polities that prevent the two countries from purely focusing on one another. If the US and USSR aren't the only powers left to stare one another down, they won't be able to have a death struggle without worrying about another faction taking advantage of the situation.
Maybe Britain takes a Gaullist route post-war with regards to its relationship with the USA. A UK-France alliance split from the US and a China split between a Nationalist South and a nonaligned communist North might be enough for such a situation to pop up.