Moving iPhoto library folder to new location

My pictures in iphoto are starting to take up a lot of place on my hard drive to the point where it's painfully noticeable- my computer has slowed down a lot. In the past, I've solved this problem by burning my pictures onto a cd and then deleting them from the computer and starting over new. However, I am currently without blank cd's and with a huge external harddrive. I was just wondering if anyone knew if it is possible to change the location of the iphoto library folder to my external so that the pictures will use up space on the external and not on my computer. I've done this with all my music in itunes and it works quite well. iphoto just doesn't seem as well prepared for this option. Has anyone else tried this with success? Or failure? Any other recommendations?
Thanks.