from the best of my knowledge the return wires are usually all yellow.. I would know were to start experimenting if it was mine.. but I would expect to blow the ballast worst case scenario..
I would take the pair of blues and twist those together and put them in 4
I would take the pair of reds and twist them together and put them in 3
the yellow would stay in 2 going back to the ballast
and the red and blue going to the ballast I would put together and put in 1..
I take no responceabilty of this working or damaging your ballast or you for that matter.. thats just what I would do if it were mine.. Good Luck.. :P
. I would expect that to work.. I would just be more comfortable with it if the other return lines were yellow like Im accustomed to seeing... I hope this works for you!! :P :P :P