Want to tell co-worker crush I like him while we're at work together...any advice how I should tell him?

Look at my previous questions for the specific details of my situation. Basically, I like a guy I work with, and I think there is a good chance he likes me as well. Problem is that he leaves for college on around August 20, and I'm going away from July 29- August 8. But we're working together with no other coworkers in about 9 hours from now lol, so I was thinking of maybe telling him my feelings toward him then. But I've never done anything like this before, so I need some advice as how I should go about it. We work in a library, so often times we're in the back room together, either helping patrons or just sitting and talking when no one needs help. Any ideas how I could start a convo that could lead me to tell him I like him? Or should I just be like ';I gotta confess something to you';? Or what? Lol, seriously, any advice would be greatly appreciated! I'm still not positive I want to tell him on Saturday, but if someone has good ideas, I might just be brave enough to do it! :)Want to tell co-worker crush I like him while we're at work together...any advice how I should tell him?
Yeah, you should. You know he probably is waiting for you to confess first, do it like you said. And i assure you that once you do it, you will be so happy and relieved.