This could be wrong, info is from this Reddit thread. I couldn't find anything on this on the Gentoo wiki.
The livegui password is random. If you're locked out, you might be able to switch to a different tty using Ctrl+Alt+F{number}. Try all the numbers, Ctrl+Alt+F1, Ctrl+Alt+F2, and so on, until you get to a console. But this may not work, it didn't for me.
In the case that it doesn't work, you'll just have to restart, then set the password manually once it autologins for you (for gentoo
with sudo passwd gentoo
, and for root
sudo sudo passwd
).
In the case it does work, you can switch back to the GUI with a Ctrl+Alt+F{number}, probably Ctrl+Alt+F1.
Warning: This guide was made by a noob, any applicable corrections would be much appreciated.