WINJUPOS should allow you to match up skewed R,G,B images and then combine them - the image measurement process (adj.) rotates the three channels to present the ring pattern horizontally aligned and the combine process (under tools) then corrects for planet rotation over your imaging period. Be prepared for a steep learning curve though. Piotr Malinski did a good tutorial on the parts of it that you will need to use, but the package is not user friendly - very powerful though.
http://www.rkblog.rk.edu.pl/w/p/plan...tion-winjupos/