Here's my version of that shot:
Remember this was actually scheduled to record the impact that never happened - 2007 WD5.
I've posted a couple of other Mars views in my Flickr gallery, all of them processed by interpolating the wavelengths of each filter and running them through CIE XYZ color calculation code - no other messing around with channel balance and tweaks. Any slight color differences thus arise due to a different filter set. A couple of takeouts:
An animation of 11 frames showing Mars going through phases over a course of 1 Earth year.
In terms of color accuracy, this is probably the best available combination I've seen with Hubble. 4 filters - actual red, green and blue wavelengths plus an additional one in between red and green as an extra data point in interpolation where it visually matters the most.