To those who don't know. You need 6 to enter. However, you can have the other players force d/c while entering. They get to keep thier permit, and you get to play solo... or with however many people choose to go.
So soloing is possible, but I have never done so. My group just used to use this trick if someone wouldn't be able to stay long, or to help out friends if they're 4-5/6.
90: WAR MNK RDM NIN BRD SAM DRK PLD BLM
Maat's Cap brought to you by actually leveling my jobs.