Can we set Process Instance Description and display it in task list in BPMS 6

Issue

We need to display information on task list so that the end user can locate the task without going through the full list. So I am setting a variable firstName as a process instance description. When I start process instance and provide the data for variable, it's not setting it to the description. How do I pass variables to process instance description when starting a case or via using script? How do I add additional custom columns to task list so that they can be searched/filtered ?