My 8 year old broke his nose a few months ago. I posted a thread very similar to yours hoping to find someone else who'd been through it - no luck.
My son broke his nose while at school, so I got the dreaded "something terrible has happened" phone call. I took him immediately to our pediatrician who said "Yep, looks broken to me, you should see a specialist ." He sent us immediately on to an ENT (ear, nose throat) specialist who again said "Yep, it's broken alright." She basically manipulated the nose back into place using her hands and a few odd instruments and sent us on our way with a note to excuse him from PE class and instructions to return in 6 weeks to be sure it had healed correctly. She said to return earlier if it seemd to be getting crooked, or if the pain increased instead of lessening over time.
DS looked like hell for 5-7 days with swollen nose, two black eyes, scrapes and bruising - but these are really cool badges of honor for a third grade boy, he loved it! It healed perfectly with no problems at all. When I took him back after 6 weeks the doc said it looked great and gave us the ok to resume normal activity. DS looks just the same as before. It did hurt when he sneezed for quite a while, but even that is fine now.
Good luck, let us know how it turns out!