The 3rd place team should get advantage over 4th/5th/6th, and 4th should get an advantage over 5th/6th. So:
3rd place straight to final
5th v 6th over 2 legs
Winner of 5th v 6th plays 4th over 2 legs
Winner of that plays 3rd in final
Same number of games but 3rd place get the advantage they...