Other than the Pelican Parts (ie 101 Projects, basically) I only found one write-up online...this one:
Boxster Projects | Brakes | Bleed and Flush
They seem to go along with Wayne, ie to start with the outer. Looked in my Bentley shop manual and, while they describe the procedure, they didn't even mention "inner" vs "outer". I've done it twice, and I honestly don't remember which way I did it. I'm not a seasoned mechanic by any means, but I really can't see how it would matter a whole lot one way or the other.