How to replace a astro window regulator?

This is a complicated task. My friend who is auto-friendly ended up taking his van to a mechanic to replace both the driver and passenger window regulators. The astro van is notorious for this kind of repair. It cost him $400.00 including tax for each regulator.The regulator itself is about $200.00- $250.00. I am going to have a look at my own van as my passenger window will not operate at all. Will let you know what kind of luck I have if any.