For those of us who don't have an available modifier key (or at least one that's accessible without looking down at the keyboard), is there a way to use a prefi

For those of us who don't have an available modifier key (or at least one that's accessible without looking down at the keyboard), is there a way to use a prefix key à la ratpoison and stumpwm? There's a patch for dwm that provides that functionality, so I assume it wouldn't be hard to add for goomwwm if it's not currently supported.