This thread might be of help:
http://www.tfproject.org/tfp/showthread.php?t=98967
I answered a lot of questions there about getting assistantships for a liberal arts degree. If you are planning to get a PhD in psychology, chances are that you will get funded for a significant portion of your degree simply by being a TA or RA. In other words, you should not need to "work" your way through graduate school.. it's not like undergrad, at least not in your field.
If you don't know how this system works, I highly recommend you get the book "Getting What You Came For: The Smart Student's Guide to Earning an MA or PhD" and familiarize yourself with academia. It's a whole other world compared to being an undergraduate.
Good luck, and let us know if you have more specific questions.