According to "pwb.py login -help":
-force Ignores if the user is already logged in, and tries to log in. -pass Useful in combination with -all when you have accounts for several sites and use the same password for all of them. Asks you for the password, then logs in on all given sites. -pass:XXXX Uses XXXX as password. Be careful if you use this parameter because your password will be shown on your screen, and will probably be saved in your command line history. This is NOT RECOMMENDED for use on computers where others have either physical or remote access. Use -pass instead.
but using "pwb.py login -all -force -pass:xxxxxx", yields:
To force a re-login, please delete the revelant lines from '**\pywikibot.lwp' (or the entire file) and try again.
Password for user MalafayaBot on wikiquote:ka (no characters will be shown):
That is, neither it did a "-force" (apparently, I have to do it manually by deleting the file) nor it assumed the password I passed in the command line (it's asking me for it).