never done it with soil, but this is how I would do it, get a pump, a water hose splitter, some hose, a reservoir and a digital timer. Hook up pumps/hoses. Set timer to however long you want to water. Place pump in water, place reservoir under plants, route hoses to plants and allow plants to drain into reservior to help prevent overwatering.
There are tons of videos on making watering systems. I Grow Chronic! which was on this site somewhere show an easy basic system.