Seeing as there is some demand for this sort of thing I've gone about reskinning imperial/shogunate units to have their vanguard colour scheme regardless of clan colours. The immediate effect will be that these units will have a different colour to the rest of your men. Should hopefully make them stand out and feel more special in your mass of dark green/blue/brown clad infantry.
Preview pics - colours and design are taken from an Osprey book on the matter.
Imperial guard infantry
Imperial guard cavalry
Shogunate guard infantry
Shogunate guard cavalry