The Liberty CRD, like most modern US diesels, has an intake system as shown below.
Daimler-Chrysler's solution to the problem is simple. They deny there is a problem. They replace parts until the warranty runs out then it becomes the owner's problem. Owners who plan to keep their vehicles for a long time are forced to come up with their own solutions.
Some people eliminate the oily crankcase air by disconnecting the hose and venting it to the atmosphere. This is called the 'elephant hose mod'. Others insert filters into the line to filter the oily component out.
Eliminating the soot getting back into the intake has an easy fix. Unplug the MAF sensor at the outlet of the airbox. The only function of the MAF sensor (on this motor) is to provide feedback to the computer of when the EGR valve is opening and closing. If you disconnect the MAF sensor the computer can't tell if the EGR is working, so it keeps it closed...no more soot gets put into the intake. It sets the engine trouble light but doesn't put the Jeep into limp mode.