I had a problem. I do not know how to print two nozzles simultaneously. Do you detailed instructions on how to do this using Slic3r?
for use PVA it's juste set option inside software, but for use tow color I never found how.
Is this what you're looking for?
in short: if you only want support to be a different nozzle you can edit the settings of a material. if you want 2 colors on the same object you need to create 2 separate 3D files ( 1 for each color) and place them together and choose 1 separate material settings.