I'm not really a crammer, but I've just found out I'm going to have an interview, and while they love my resume and experience, it's going to come down to Japanese ability.

While I'm very comfortable in normal conversation, my business Japanese is... non-existent. (I guess I'll just end everything with と思います　and んです haha)

They want a good Japanese speaker because I will be working daily with Japanese staff, even though the company is American.

Any resources out there that would be able to help me study for this interview? Any recommendations?

Just speak with regular polite Japanese and maybe throw in some simple keigo phrases. Don't try to go overboard with keigo if you are uncomfortable with it because they will doubt your Japanese abilities more than if you just stuck with the polite form.

If you can do that then you'll be fine.

Good point. And my understanding of keigo far surpasses my ability to use it, so even if the interviewer uses keigo, I should be ok...

Still, it would be good to look at some resources.

Any library in Japan is going to have a dozen books on keigo. Although native material might be too complex.

Most basic Japanese textbooks cover keigo in some degree. GENKI II gives a good explanation of the basics and you can get enough info from there to impress your interview panel.