The same way I guess, the way I do it:
To update:
startup.py in my extension contains:
from subprocess import call
token = "github_pat_654rthtsrfhn"
call('cmd /c "pyrevit extensions update my_toolbar --token="{0}""'.format(token), shell=True)
To install
from the command line (either in admin or non admin _ you need to check how pyrevit was installed running pyrevit env to see if your pyrevit clone is there):
pyrevit extend ui my_toolbar https://github.com/jmcouffin/my_toolbar.git --dest="C:\pyRevit" --token="github_pat_658rtssrtfh6"
you could us the cd C:\properFolderLocation command to make sure you are in the proper folder