I think the message here was "notebook implementations aren't all the same and degree of support varies between vendors". As an example, some vendors offer BIOS support for switching between IGP and discrete graphics while others do not.
The amd.com web pages mention that switching is supported on Linux for AMD APU + AMD discrete systems but requires manual switching and an X server restart... that also matches my understanding of what is in fglrx but I haven't actually tried it myself.
For the more general case support appears to be Win7-only and vendor-specific :
I don't know what model of notebook you have but it appears that HP have recently released BIOS updates to support "fixed" GPU switching (ie one or the other) for some models :
The associated download pages only talk about Win7 compatibility so usual caveats. I think this is probably why the support group said "talk to the vendor".