Hi.
Yes, thats great, that thread shows the same thing, I just call my blending map an ID map.
To connect the blend utility to the layered shader, open up the attribute editor for the layered shader, and simply MMB drag the blend node onto where it says colour for the layered shader, and it will attach.
The problem with using layered shaders like you would normally for layering textures is that Mental Ray sometimes can have a hard time with them, but it seems to work fine if you use the mix map method.
LisaG