Here is what I did and it worked great -
I dropped a 460 gph pump into a 35 gallon trash can and hooked up a manifold with drip lines and drip sprinklers. The pump was plugged into a $20 digital timer than could turn on/off in increments of 1 minute. The real task is adjusting the individual sprinkler heads and adjusting the minutes per day and days per week to run the pump - once completed it works great.
At first I tried running loops around the plants with perforated drip line but found it much more difficult to control the rate (and they tended to clog). The sprinklers however are easily adjustable and really just drip - 4xx gph pump isn't enough to spray water.
I think this is the key component you're looking for - hydrofarm dual outlet digital timer. Can have up to I think 12 settings, you can choose single days of the week, every other day..., increments of 1 minute on/off.
http://www.google.com/products/catal...ed=0CDQQ8wIwAQ