I think the best you can do is; Isolationist but heavily armed USA (so I can stay isolated), USSR (+ OTL Warsaw pact minus Poland and Czechslovakia) , PRC (historic split between Maoism and Marxist-Leninism), Third Reich (incl./ controlling: Poland, France, Spain, Italy, Benelux, Denmark), Commonwealth (UK, Canada, Oceania, India, Africa below Sahara, Norway, Sweden)
Problems:
1. USA would find it very hard to stay Isolationist with the threat of Armageddon.
2. Early development of Nukes needed to Stop USSR and Third Reich wiping each other out.
3. Why don't PRC and USSR as fellow Communists gang up to take on the world?
4. How does the Commonwealth hold together? Africa and India would be tempted to join the likes of Japan and be non-aligned, while Canada could easily leave the UK to fight alone and hide behind the US's skirts.
5. In OTL there were only three real lines of friction: US vs. USSR, US vs. PRC, USSR vs. PRC in this world there are 25 lines of friction. So the chances of a nuclear exchange are massively higher.
6. It is a zero sum game so why don't various sides with a lot in common (USSR and PRC), (UK and USA), (Third Reich and PRC (not a threat to each other and both neighbouring the Commonwealth and the USSR)), gang up to reduce the no. of players, the threat of nuclear annihilation is bound to help but you have a lot more potential for two crazed nutjob's who don't care to get their fingers on the big red button.
Anyway as the above points point out it is quite difficult but I think this is the most plausible way to have a five sided Cold War.
Edit: Four sided is a lot easier simply merge the Commonwealth and the USA into the Allies and voila a lot more plausible though it still has a few flaws (PRC and USSR not finding common cause for one.)
I really think that a six sided Cold War with all sides fitting the superpower description (large nuclear arsenal, strong conventional forces (whether due to sheer manpower (PRC), high tech (USA), or a mix (USSR)), with an economy big enough to maintain such capabilities without being on a permanent war footing (by which I mean Germany in 1938, not USSR in 1980.)