This is a stretch for a PNWSOTA summit report but, if you find yourself in Seoul with a few hours to kill, this could help you navigate. My son and I were able to activate this summit after doing the normal tourist activities.
The Korean Amateur Radio League will help submit your reciprocal license application based on your FCC license which will grant you similar operating privileges. See this page for instructions. So for this activation, we were operating as HL1/NE7ET and HL1/K7HY. You will need to submit your application at least 4 weeks in advance. Don't forget to print out a paper copy of your reciprocal license when you go.
Public transportation is very convenient in Seoul. We rode the Line 3 to Maekjae Station (37.582839696171774, 126.95022759719707) and backtracked south to the cross street Tongil-ro 20-gil. Follow this up, up, up to the trailhead (37.58127678920476, 126.95454835492947) which is at a small playground. The trail starts there and goes up on mostly protected stairs until the old city wall at (37.582402, 126.957561). From there, head left following the old city wall until the summit. There is one section of stone steps that have eroded sufficiently that they installed steel stairs. Since the summit is enclosed by the wall and a fence, there isn't a lot of space to setup a long wire. It could probably be done but we chose to just do 2m. It took us around 45min to climb to the top and around 30min to descend. See this link for another route.
We were able to work several local stations by calling on 145.0-fm and then quickly QSY to 145.040. This included a S2S with DS1TNR on HL/GG-065!
This was a very enjoyable activation, complete with overflight from around 20 ROK airforce jets training for an air show.
If you have more time, there is another summit An-san (HL/SL-008) just across the highway from this summit starting from the Maekjae Sky Bridge. Or, closer into the center of town, Nam-san (HL/SL-009) is just a 1.5 mile hike from Seoul Station. We started too late on the day our flight home was leaving to get there in time.