The owners manual for the 2008 liberty is real clear on the steps to take for towing.
I had the blue ox base plate installed, and aventa bar,,,,a test tow was nice.
I am still looking at braking systems.
I believe the 2009 will be the same as the 2008 for towing. But again,,,the owners manual is the bible for me.
I also installed a battery disconnect,,,not a hassle to disconnect when setting up to tow.
A lot of folks have indicated that they don't disconnect the battery, and have not had any negative impact.