RustyTrichome had a thread about watering during vacations. He explains it well, but in short, you take a bucket of water and a piece of string. Place the bucket higher than your plant. Put the string in the water bucket and have it hang into your plant bucket. It takes a little bit of trial and error with different kinds of string to get the right flow of water. Here are a couple threads:

http://boards.cannabis.com/1782869-post5.html

http://boards.cannabis.com/plant-pro...-watering.html

Good luck!