Hey there,
I've hadn't heard of any ice hockey, possibly Seoul, if any. Check out Seoul Scene website. However, there is a ball hockey "league" or group in Busan. I think they play every Sunday at 11am next to Sajek Stadium (Home of Busan's baseball team, the Lotte Giants). As far as I know anyone can drop in and they even rent sticks across the street. There may even be two games each Sunday, one on roller blades and one on foot. Both Koreans and foreigners play. Check out the website pusanweb.com and look under the sports link. Goodluck and let me know how it goes if you make it there.
Cheers
Chris