ok, I have commited and pushed to rawhide and f22 what upstream
commited.
Basically a xfconf key that (when set) will override all the hard coded
junk in the xflock4 script.
You can create/set it with:
xfconf-query -c xfce4-session -p /general/LockCommand -t string -n -s
"xscreensaver-command -lock"
etc.
Please test.
https://admin.fedoraproject.org/updates/xfce4-session-4.12.1-2.fc22
kevin