Looking for koji hub policy advice

[Pat Riehecky]

I'm looking to fix up our Secure Boot infrastructure for Scientific Linux.

I noticed the fedora koji has the kernel building against a specific 
channel.  I assume so it can be directed to hosts with the necessary tokens.

Alas, I've not found the necessary hints at 
https://fedoraproject.org/wiki/Koji/Policies  for how I'd write such a 
policy.

I'd also rather not remove the default policy[1] in the process.

May I request some help?

Pat

[1] https://git.fedorahosted.org/cgit/koji/tree/hub/kojixmlrpc.py#n492