Hi @rodyb,
To answer you question directly: You can just login all the users and return an array of the tokens which will then be provided to the default functions, which can pick up one from it. I have longer explanation with more info here.
I would (as I mentioned there) kind of recommend to not do it in setup but instead login in the first iteration of each VU and use that. This both parallelize the login to the VUs - which is a problem when you have to login thousands of users in the setup and that takes forever. And also IMO more closely will resemble the real world where users need to login in order to do something.
Hope this helps you 