Seems to me that you could adapt a simple circuit like this (see figures 6-7) here-> http://www.nutsvolts.com/magazine/artic … r-circuits
without using a micro. Simply connect the GRN led to outputs 0-3, YEL led to 4-5, and RED led to 6-9 (or some combination that results in the relative on time for each led). No micro needed but you would have to find the parts (555, 4017B, etc).