I take it you are new to this type of car and saw someone with a snorkel and thought they were cool? QUOTE]
Dang Black.. go easy! Bad enough he got suckered into a unibody jeep!
The truth is snorkels can seen as "poser" since so many have them but just want to look the part. The reality is they are but one part to a total package to making a jeep more water friendly. They also help with heavy dust areas. But I'll stay more towards the water for you..
military Jeeps (and military vehicles in general) are specifically designed to ford water crossings. But if you check out the link you'll see even that was a work in progress. One advantage the military has is most of their equipment is very spartan and simple. We don't have a lot of fancy sensors and our electronic ''junk'' is pretty waterproof. But as the civilian Jeeps progressed they have to keep up with modern saftey and emission standards. Also they have left thier more utilitarian roots for a more car-like package. And while I don't own a jeep newer than 91 currently... Even that is a far step from either my Scrambler or my 67 Commando. All things considered I feel you would have been better served going with the JK over the liberty but thats water under the bridge. Perhaps with some dedication, research, and effort you can make the Lib more trail and water friendly. Just be prepared to work for it. The Lib is very car like IMHO which makes a good way for jeep to sell to more people but less desireable for harder trails. It sits to low, has smallish wheel wells so tire size is limited, and doesn't offer much visability out the back. Plus the very car like interior doesn't bode well should you actually sink the thing past the door sills... lots of carpet and plastic stuff to trap water. While fancier than I can imagine, at least the current jeeps still maintain some level of water resistance inside. And while more work you can also remove the carpet to dry and clean everything.
The biggest thiongs to worry over with your jeep is water entering the engine (quality sealed snorkel) and drivetrain components (extending vent lines as mentioned) and then mud/water effect on electrical components. Playing in water and mud allows gunk to get places the engineers kinda hope it doesn't. Sure, most stuff under the hood or under the jeep is basically water resistant. But that is to the limit of about a deep puddle from a rainstorm. They don't engineer the jeep to swim anymore so they kinda hope you don't do it.
I wish I had better advice for specifically what you could do to make it work. Its just a fairly involved process of sealing everything and making it as water proof as possible. And don't forget that the exhaust should be extended as well... If you get stuck half way across and the snorkel brings in air the engine should run. But if that water backs up the exhaust the jeep may die. Then, as soon as you open the door to hook up a winch... woosh! In comes the stream.

makes a bad deal worse...
http://www.cj3a.info/sibling/cjv35u/evolution.html