I went with Koryo tours in August and saw the mass games. It was a great time and Koryo tour staff were very helpful, professional, and fun.http://www.koryogroup.com/ You MUST travel with an organized tour, and I believe that to get a visa you must go to or through the North Korean embasy in Beijing. While in the country, you are expected to stick with guides, take photos when allowed, and otherwise be respectful of guides and their rules.

Pretty easy actually. You do need a visa and have to join organized tours or have a state assigned guide with you at all times though. Most people fly in from Beijing. You can also arrive by train. Look up companies like Koryo Tours.