OH, the fogs on the Liberty are included in the headlight assembly?
That might make upgrading a lot easier.
Doubt it but they might of used a different headlight connector for the fog option which needs to be verified.
Need to do some homework on whether the headlight connector can power the fog lamp.
If not you'll need to buy the correct connector or get one from a junk yard.
Keep in mind OEM fogs when enabled are designed to work only with low beams and turn off when brights.
With some fancy wiring, maybe a schematic, a relay and an ON-OFF-ON 3 position switch then;
ON 1 position = fogs on only with low beams (OEM compliant),
OFF position = fogs unconditionally off,
ON 2 position = fogs unconditionally on (typically for off road or lonely road use).
I wired the aux. driving lights on my XJ that way and it works great for all kinds of different driving conditions.
Of course you could wire it up with a simple ON/OFF switch but there's a very remote chance you could get pulled over by a Barney Fife if you forget to turn off the fogs when the brights are enabled.
To get them OEM compliant you could energize the relay coil from the low beam power wire with the switch in series.
But that would depend on if the low beams stay on with the high beams which is the case with some cars.
Whatever route you take, make sure the main fog power and the relay's coil power are properly fused.
Good Luck and let us know hot it turned out.