remap them with xmodmap
First, generate the current keycode map:
$ xmodmap -pke > .Xmodmap
To detect what the keycode is for specific key, use command:
$ xev -event keyboard
Add
usermodmap=$HOME/.Xmodmap
sysmodmap=/etc/X11/xinit/Xmodmap
if [ -f $sysmodmap ]; then
xmodmap $sysmodmap
fi
if [ -f $usermodmap ]; then
xmodmap $usermodmap
fi
to your ~/.xinitrc.
XF86 keysims are listed here