mock config per tag

[Michael Cronenworth]

Is it possible to attach a mock config to a particular tag?

Scenario: Fedora host and build system. I am attempting to build a SPEC 
that checks if it's building under Fedora or not (can be if %rhel 
exists, or /etc/fedora-release exists, etc) but it currently fails for 
my RHEL 5 build tag (i386, x86_64) as it thinks its on Fedora. The SPEC 
is setting ExclusiveArch for i686 for Fedora and i386 for RHEL. This 
works fine if I build natively on a RHEL box and Fedora box, but I'd 
rather build it under Koji.

Would setting a mock config even help? Is there a more appropriate way 
of handling this scenario? Google searching and wiki searching hasn't 
turned up much.

Thanks,
Michael