Generate tokens using Joken in Pow

I’m trying to use Pow as library. I’ve followed the API guide and it seems like it uses Phoenix.Token for generating access and refresh token.

Though there’s no problem with tokens generated by Phoenix.Token I would like to use Joken instead for generated JWT. Looking at the source code, it mentioned that I needed to supply the MessageVerifier option in the config but I don’t know where to start.

I would like to ask if you have any guides on generating tokens with Joken or other JWT libraries.