How does one do this? I checked the docs but i kept getting locked out with sys.usb failing on startup. Does the 4.1 section help? If so, i may need a little clarification. 
Hello. I installed sys-usb few days ago. I just follow docs, and it’s just works. I used Debian-11 template. If you use community templates (gentoo, parrot, etc, it may need additional configuration. I don’t use Fedora, so I don’t know anything about Fedora-specific troubles, if it possible.
Maybe you need to add more RAM to sys-usb (by default it is only 300 MB, which may be insufficiently). On my system sys-usb works with 300 MB RAM, but I add more to avoid using swap.
Can you describe it in more details?
If you get an error when sys-usb is trying to start then maybe you need to add no-strict-reset option:
PCI troubleshooting | Qubes OS
try adding qubes.skip_autostart kernel option on grub menu, so your kernel option would be …rhgb quiet qubes.skip_autostart.
press e for editing grub menu then f10 for continue boot.
after login run qubesctl state.sls qvm.usb-keyboard then relog.