I did this using a kit from Autoloc. I am pretty sure this is the kit.
http://www.autoloc.com/catalog/Power-Wi ... d-Switches
I think you can find it cheaper if you just Google the brand and part number.

 

I did the conversion in my 02 Sierra. No, you don't need to change doors. There are kits available that will fit onto your crank windows after removing the manual handle. Or, you can replace the manual regulators with electric ones. Replacing the regulators is a lot more work but you will have a factory look when they are completed. Here is where I purchased everything I needed .
https://www.a1electric.com/index.htm
A Google search will reveal many vendors selling the conversion kits.

 

i bought this conversion kit http://www.a1electric.com/Merchant2/mer ... ode=GM83-K from a1 and put it in my 02 Silverado, it was extremely quick and easy to install no hassle at all hope this helps

 

I just did my manual to electric I bought 2 electric regulators with motors installed them perfect fit to windows and holes are already in door I used the wiring harness from a kit i bought( didn't use junky motors) and as of now I have electric windows 2 knobs on driver side 1 on passenger side. Now to hide the hole where knob used to be but not having to hand roll down windows or reach over and roll down passenger side is great

 

Now to hide the hole where knob used to be but not having to hand roll down windows or reach over and roll down passenger side is great

I ordered the kit from A1 Electric. I plan on putting the switches where the window crank was. That way I won't need to find something to cover the hole.

 

I should have thought of that before making holes in the arm rest