Hi Samuli,
Probably the last two really... in bold below, (or maybe all three 
):
Which part do you want elaboration on? The bit of having different SAML configurations for the two URLs, the bit of assigning custom UME attributes based on SAML assertions or the bit of how to assign portal content based on custom UME attributes? I don't remember seeing a document discussing all 3 but I remember seeing separate documents for each.
Thanks for your help,
Simon