According to the aforementioned poster's room mate, an unidentified former GW employee, Roland's introduction of his co-star "It's Kevin", or "Here's Kevin", corrupted to "S'Kevin" was the true origin of the name "Skaven".
However, several other posters confirmed having heard the same story regarding Roland Rat, and a bit of googling turned up several other instances scattered across the web. Which perhaps means I'd just come across the very first Skaven urban legend.