"I want to use Brainstorm for source analysis of EEG microstates, but I'm not sure how to proceed. Could you please guide me and provide any relevant tutorials or resources?"
There is currently no Brainstorm plugin tool to run micro states analyses. However, you may refer to the following documentation pages that describe how the Cena toolkit previously worked with Brainstorm. Unfortunately, Cena does not seem to be continuously maintained, but you may want to reach out to its developers and look into how to revive the Brainstorm plugin yourself.
https://neuroimage.usc.edu/brainstorm/Tutorials/MicrostatesCena