The Eirraucs' first (and only, up to my knowledge) appearance was in the 'Star Wars Galaxy Magazine' #9. I have the old WEG stats, if any ones is interested in converting them or something.
Here is what the magazine had to say about Eirraucs:
"The peaceful natives of Eirrauus are remarkable for their immense hind legs and have a graceful 'leaping run' which can propel them to speeds over 80 kilometers per hour. They have two arms; the middle pair of 'mid-legs' are used as arms and forward legs while running.
"Resonsibility to the group is a common Eirrauc trait. They are hard workers and shrewd thinkers, with a great fondness for the arts. Eirraucs tend to shun modern technologies, believing that they are dangerous and uncontrolled; they strive to maintain a balance between technology and 'the natural order of things."
Medium: Ink, Colored Markers