I have done some research and found the Louisiana Tigers had a blue top, white pin-striped type trousers and a red hat/fez. Obviously, I won't be attempting pin-stripes and the trousers will be plain white. The other Rebel unit will have a red top, white trousers and a red hat.
For the Union, 146th New York Volunteers (Garrard's Tigers) seem to be wearing a pale blue top and trousers with a hat of white/red. I don't normally like to identify a particular regiment and prefer them to be generic to allow their use in any battle of the war, but will make an exception for the two above named units, one for each side.
The other two units will be in a green top, red trousers and hat and finally, a sky blue top and trousers with a white/red hat.
In the period I was away from the 6 mm project I managed to complete a total of nine units for the War of the Roses project. One unit of Bill Men, two units of archers and the first six of twelve units of foot knights. The Bill men and foot knights are not wearing the colours of any of the four main factions and so can be recruited into the retinue as required.
I will take photos of them and post them soon.