Jeseitz, probably the best and "easiest" way to convert to power windows and locks is to find a source vehicle from the same generation as your 98 S-10 and grab all of the harnesses connected to the windows and locks. In addition to these electrical components, such as motors, switches, relays, etc., you will also need to remove the window regulators--part that hold windows and moves them up/down. Buying whole doors may turnout to be more expensive as you will be paying for the door inner structure and outer skins. One recommendation is to take A LOT of pictures as you dismantle both doors.
When I did this conversion on my 87 El Camino, I opted to buy and install new switches, motors, relays, and actuators to eliminate potential issues in case there were problems. That being said, as we car junkies all know, just because it is new doesn't mean it will always work like it is supposed to! Good luck!