Fedora 29 ( gnome ) live - switch between wayland and xorg

How can I switch between or from wayland to xorg on a fedora-29 live session WITHOUT rebooting or by specifying it during startup?

It is important, that it works from a live session without having to install fedora 29 .

Sometimes there are posts elsewhere advising to log off and select gnome xorg via a gear symbol in gdm, however here no such gear symbol seems to appear / exist when logging off in the live session .

Adding WaylandEnable=false to /etc/gdm3/custom.conf might perhaps be the start of a solution, but when I try to restart gdm afterwards, it does not start any more and if I try typing
in a terminal ( switched there by str-alt-f2 for example ) it does not work, too.
Is it possible to start the xserver with the fedora 29 ( gnome ) image?

Thank you for your hints