Disclaimer/CMA time: I know it's neither elegant nor pretty, but I modified the ?login and ?rancid scripts so they work for what I need them to do. I also added a line to "rancid-fe" to support the vendor "extreme" tag (and call the proper scripts)
They're all in the attached .tgz file.
It's quite possible that there is better/proper support built in to rancid or available through the forums.
And I don't know how to attach a TGZ file - I'll try to email it to you.