How do get a really shy guys cell phone number?

It all started when my friend went to her cousin football practice. Her cousin Steven brought his friend Alex with him. He's rich and really nice too. So my friend went home and I came over that weekend and her mom was talking to her about Alex. I was like who's that? So she took me down staires to get on the computer to show me a picture of him. And he gourguse! Anyway I was talking to her aunt Kris (Stevens mom) about Alex and she told me all this stuff about him then i started liking him even more. So i told her it would be really cool if we could talk sometime so the next weekend Alex went over to Stevens house and they called me. It was great that they called but alex is extremely shy!!! So mostly I talked to Steven but I really wanted to talk to Alex. Now I still want to talk to him but I need to get his number and I don't no how to do this. I don't want act like I'm desperate or I'm being pushy anything it's just we have so much in common and I really wanna talk to him but I Ned to get his number with out sounding like being pushy,or a creep,or desperate, so anyone please help me here.