Interviewing for teaching position in a department that is similar to, but not exactly, my own field

For a teaching position, it should be much more important to your interviewers that you have a firm grasp of what you will need to teach for them than that you be current on the most cutting-edge research in the field.

Spend some time looking at syllabuses for the courses they want you to teach. Syllabuses from the school itself, of course, but also a few from other similarly-situated schools if possible. If the department's own class materials aren't publicly available, don't hesitate to contact them directly and ask if they could share this with you. It should be a good sign to them that you want to do a bit of research into the position.

Of course if there is anything in the basic classes that is currently really beyond you, you can do a bit of background reading. This shouldn't involve entire books or fields of literature, just enough so you know what more you would need to do to prep the class.¹ Again, you don't need to be ready to teach the class when you arrive at the interview, but you should be ready to explain what steps you will take to get ready before the class itself begins.

If I were interviewing you, a great answer to this question would be something like (assuming these are the right topics, scholars, etc.):

I feel like my training in Field N has really prepared me for [these specified aspects of the course] as there is a lot of overlap with [these theories/methodologies/methods/scholars]...I do need to brush up on Scholar X's work and also get a better grounding in Scholar Y's theories.

Also acceptable would be:

I'm well prepared for [these topics/methods] and will need to delve a bit deeper into [these very specific sub-topics/methodologies/methods].

A less comforting answer:

I can teach anything; I just need to learn more about [the main topic of the course]

And this answer:

What does that class cover again?

would be a big red flag.

You should also be prepared to answer questions about your future research interests, what kinds of advanced topics you might teach, and how those interests would fit with the needs of the department's students. Be honest here, but see how you can tie your expertise and interests to the subject at hand.

Finally, if you really want to be sure you at least know major journals and names in the field, you should ask a subject specialist. Either a friend or colleague in the field or, barring that, a subject-specialist librarian can probably give you the top-5 titles and names you should know, as well as any recent controversies or important advances in the field, just so you aren't left nodding along if they come up over lunch.

Good luck!

¹ It doesn't sound like this is your situation, but if you need to do a LOT of reading for even the basics, then this may not be the position for you. For example you don't want to be in the position of needing to take the intro course in order to be able to teach it, just for your own sanity's sake. (Though this does sometimes happen...my high school French teacher told us that she learned right along with her first class of students, as she hadn't ever taken a French class before she was assigned to teach it!)