Running Weston under Trisquel GNU/Linux is very easy.
Open a terminal and run:
sudo apt install weston
Then preferrably logout. Then switch to a tty (e.g. by pressing Ctrl+Alt+F3) and login with username and password. Optionally stop the lightdm service, to reduce resource use:
sudo systemctl stop lightdm
* lightdm
will automatically start when you reboot.
Run:
weston-launch
This should launch a weston session. Press Ctrl+Alt+Backspace to logout of the session. Check here for other keyboard shortcuts