Maybe if the ring was assigned as a subentity, but I don't think planets support subentities. The problem with rings are that they are essentially rocks and dust floating around the planet. To produce this in Oolite, you'd have to spawn about 300,000 asteroids around a planet in a ring shape, which would probably cause some loading issues on slower machines.
Its a shame really, there was a game called Klingon Academy that let you fly into Planet Rings and it was pretty cool. This would be a good idea if it is possible!
Ok, i've finally finished an initial release for System Redux Replacement Textures
Just unzip the two files and copy/paste the contents into your System Redux textures folder (I would recommend backing up system redux textures before doing so)
You will need a fairly decent set-up to run these textures as the files are rather large
Please take screenshots if you find any errors...I've tried to check them but I may have missed something...I will fix and upload a new download for any errors reported