WCF Sample using Role Membership that actually works

[M]

Hi,

I want to create a WCF Service and Test Client, with the WCF Service
accepting a username and password sent to it from the client (using
clientcredentials) and validating the user using role management.

I have tried this how to: http://tinyurl.com/lktdfz but can't get it to work
properly.

I can create the Service ok, get it to validate a user using role management
via the aspnetdb, but I can not persuade it to accept a user / password of
my choosing, it just seems to want to use windows authentication in some
guise or other.

When I start attempting to add the certificate I just get into a world of
pain.

Does anyone have a sample app and / or a 'How To' that actually works?