by AlderaanDuran

the speedy launch-to-docking was accomplished by "using intricate ballistics maneuvers [that] succeeded in cutting out around 30 orbits and 45 hours from the flight time to the ISS."

Instead of a couple days, they were able to dock just 6 hours after launch. They've done this with cargo a few times, but never people. It seems like the only difference is a much harder series of burns right after separation, instead of the usual timed and phased burns.

Additional reading:

http://www.space.com/20412-soyuz-one-day-spaceflight-infogra...