You can either take the exit 2 or 3 from Myeongdong subway station.
Then, walk pass 7-Eleven and GS-25 convenience stores on your right.
Walk up the hill (enlarge the map to view the path clearly) until you
find Namsan guesthouse 3, then Namsan guesthouse 2 and lastly A -Namsan
guesthouse 1 (the furthest from Myeongdong station T_T); all on your left
and walk just a tiny bit more to reach B -Namsan Tower Cable Car Station.
( I bet you will be panting by now)
Namsan Tower Cable Car Station
P.s. Don't be deceived by the map, it may look flat but the terrain is not. ㅎㅎㅎ