Slightly outside of GE, but I completed my Smart Entry enrollment at ICN, thanks to the reciprocal agreement with GE/Korean immigration. I applied about 3 weeks before I got approval, and just happened to get lucky and be approved while I was in Korea. It would have been an easy, 5-minute process if I had US dollars on me. The fee is $100USD for foreigners without a Korean bank account. So if you're seeking Smart Entry and don't have a Korean bank account to deposit the change into, bring $100USD with you or you'll have to exchange currency for a $100 bill at the exchange right outside the Smart Entry office, at bad rates nonetheless.

Also, in the approval letter you'll receive from Korean immigration, it gives you a list of places you can go to complete enrollment. Well, as a foreigner in Korea, the only places you can really complete enrollment are GMP or ICN. I first tried to complete my enrollment at the KOTRA center, which was near where I was in Gangnam, but was quickly told that foreigners could only complete enrollment at the airports. A nice waste of 20,000KRW in cab fares.

So as long as you have your passport, printed approval letter, $100USD in cash, and complete your enrollment at GMP or ICN, the completion process should take less than 5 minutes in all. It was just a simple photograph, digital index fingerprints, and deposit $100USD into a machine that resembles an ATM machine. I was able to use the benefits directly after completing enrollment to bypass significant waits at exit immigration. I was through in 20 seconds, where it took my colleague 30 minutes to clear immigration at the same time. Very efficient.