I have not done any work on the steering column to date but hopefully this will help. I would go to a salvage yard to see if they have a compariable van and remove the cable before working on yours then you will know what needs to be done without breaking anything on yours.
Here is a link for the Factory Service Manual for the villager/quest:
http://www.nicoclub.com/FSM/
scroll down to quest, click on it and choose year.
Go to section ST, I believe this will help you with procedure to replace cable.
hope this helps
From what I have been reading it seems that you need to remove the cluster and lower the steering column to disconnect the cable from the selector plate.