Had a truly lovely (and far too brief!) stay in Axl and Bjorn's beautiful home. The apartment was (mostly) easy to find--I arrived after dark, and only had one tiny mishap, walking up the left side of 54 to reach 54B, instead of the right side. It's a relatively short walk from Nationaltheatret Station, although be warned there are some inclines/steps to be negotiated, so the less baggage, the better!
Received a warm and relaxed welcome from Bjorn, who showed me around their very beautifully appointed home and gave me all the necessary details, including pointing out visible landmarks and giving me a small tourist guide with a nice map inside. The room was exceptionally comfortable and I especially enjoyed coffee on the terrace the next morning :-)
My only regret is not being able to stay longer! Wonderful hosts in a wonderful location, highly recommended.