Much as Mr Jackdaw said, the only real way to re-colour the bars atm is thru lua plugins, the beauty here is they could be set on the fly.
The pics (hopefully) attached show some modified colours for a hud I gave up on a little while ago that uses coloured windows instead of blended graphics for the vitals bars. Turning these sideways would probably be easier than the current vertical coding which was an absolute pain.
To achieve what you are after would probably require a mix of skinned vitals and re-coloured hud but would be achievable if somewhat clunky.