Just cut the crap (I mean don't play hint game) and go up to him and talk to him. Don't have to tell him straight up that you wanna be his valentine....but spend some quality time with him which will make him ask you to be his valentine. After some BSing (I mean conversations) with him you might wanna start talking about valentine's day (some more BSing) and at some point ask him if he has any plans. When ask about his plan look right in to his eyes with a smile. He will know what to ask later. And if he doesn't then I don't think you should even ask him out on a valentine's day.
and if he says NO....then you can ask me... ;)
kinda hint him clues and stuff. you never know he might think u will say no ;)
if you are standing perpendicular to him then maybe