How can I get his attention?

In this situation, you need to make the first move. It seems apparent that he has some interest in you. Make up a reason to go talk to him. If he does nothing but looks at you when your friend is not around I don't think he will be clever enough to make up a reason to talk to you himself. I'm not putting the guy down but your description is that of the classic shy guy who winds up losing the girl he wants because he is unwilling to say something to her. Good luck.

Lil advice to you, don't get your self into "Work Relationships", cause as long as you like him and in any case if you had the chance to make him notice you the result is a date and may be after that a relationship that may or may not work. if it didn't work out! you will find yourself in the middle of a lot of issues. :-)

He already gave it to you, and made a judgment call. The trick now is to make him rethink that opinion. Also remember, hooking up at work is considered by some to be low-brow. He may really like you, hence the reason he tries to distract himself with the attention of others he isn't "hawt" for.

Try this, just stare at him in the eyes, when he eventually looks back, give him a playful smile and throw in a wink.

. It may take a couple days, he may need to think about it, but he will start to pay more attention to you. However this does not mean he will talk more to you, in fact he may try to avoid you. If after a week you don't get the results you want, you'll need to try a direct approach, or accept its just not going to happen as is.

Cheers