::a little late to the party::
I have seen a few examples of coatls/quetzacoatls before, nothing necessarily
infantry sized as all are more monster sized.
One of the best examples I have seen from this site was found by
@pendrake : the Sun Winged Coatl (thread
link).
Another one I found more recently was done by a sculptor known as moonswift: a four winged creature called Kulkulkan (
link to thread and WIP process)
And there is mine

... which doesn't blow the previous two out of the water as far as style points but was pretty fast to make! (
link)
As far as more
man-sized models go, I found a few examples of some snake minis that could be more "kulkulkanized" a bit with a liberal application of feathers:
This guy from Reaper minis, painted by Antonia Vogel (
link):
THIS ONE was pretty dramatic, the serpent cultists are from gamezone, but the terrain is epic! Though it follows an Egyptian theme, that is easily remedied to change to something that looks more mesoamerican/kulkulkan:
Definately check out this
link, the picture comes from Matakishi's Tea House, and they have tons more pictures of their Conan miniature projects. I really like their interchangeable terrain setups.
And some extra cultists, no link but pretty sure they are reaper or gamezone as well:
