OK so after my failed attempt to list the possible SF permutations, stuff.co.nz have come up with this:
Scenario 1
Winners: Chiefs, Crusaders and Brumbies
Semifinals: Chiefs (1) v Hurricanes (4), Crusaders (2) v Brumbies (3)
Scenario 2
Winners: Chiefs, Crusaders and Hurricanes
Semifinals: Chiefs (1) v Brumbies (4), Crusaders (2) v Hurricanes (3)
Scenario 3
Winners: Chiefs, Reds and Brumbies
Semifinals: Chiefs (1) v Reds (4), Brumbies (2) v Crusaders (3)
Scenario 4
Winners: Chiefs, Reds and Hurricanes
Semifinals: Chiefs (1) v Reds (4), Hurricanes (2) v Crusaders (3)
Scenario 5
Winners: Blues, Crusaders and Brumbies
Semifinals: Crusaders (1) v Blues (4), Chiefs (2) v Brumbies (3)
Scenario 6
Winners: Blues, Crusaders and Hurricanes
Semifinals: Crusaders (1) v Blues (4), Chiefs (2) v Hurricanes (3)
Scenario 7
Winners: Blues, Reds and Brumbies
Semifinals: Brumbies (1) v Blues (4), Chiefs (2) v Reds (3)
Scenario 8
Winners: Blues, Reds and Hurricanes
Semifinals: Hurricanes (1) v Blues (4), Chiefs (2) v Reds (3)