Bus 52 from Wonju Station or Nambu Market (and other stops, though not the bus station) goes to Kanhyon Station. There's a bus stop ib front of the resort as well; busses to Mun-mak, though I don't know the numbers, make infrequent stops there.
There are hotels, min-baks and camping/bivy options at Kan-hyon, though on weekends and holidays, MTs (Membership Training, essentially, drinking and bonding trips for university students-- think: LOUD) are held here often. Camping by the furthest train bridge on either side of the river is an option (a few trains run nightly; earplugs are not available on site, but are a good idea!).
Look under Ganhyeon in the Search climbs thread and you'll find even more beta on getting there. It's pretty easy, even a train stop right at Ganhyeon, from which a 10min walk will get you there. Plenty minbaks and camping avail.