I don't think they've been published anywhere else than official Glorantha sourcebooks (I have some of the Finnish editions from late 80's or early 90's), but I might be wrong.
Even then, I doubt all the myths would be there in a convenient package, so I'm afraid you are stuck with in-game text.
EDIT: Whoops! Misread the dates and answered quite an old post, sorry.
Post edited January 08, 2013 by Crowned