2008 Liberty/Legacy with the Limited Edition Navigation pack have a 24 pin which is normally only partially populated. The optional AUX in factory option includes an in-line harness to give the following:
Audio L/R In
Video In
Video Out
Sub Line Out and Amp power on
I've documented the pin as viewed from the head unit. If in doubt, use the existing harness wires as reference. Note the two pins that need to be shorted to enable the AUX input. When enabled, the AUX input can be switched to by pressing AUX or by selecting the AUX option in the Audio Screen menu.
Furthermore, note the pin labelled "Park Break", I suspect that if you disconnect this and short the pin (on the head unit side) to ground the Nav/Video lockout will be removed! I haven't tried this myself, it's for a future project (probably when I get around to putting in my sub).