I know that's not a terribly helpful comment on my part, but it really is one of the very basic concepts of the game -- the whole reason Shadowrunners use magic and cyberware and stuff is to let them do things normal humans can't. They can leap tremendous distances, shoot a submachinegun built right into their arm, sprout claws and razors to tear someone up with implanted weapons, fire a weapon with ridiculous accuracy, punch through an engine block, or...yes...even move amazingly quickly.
As for how it would look? Just watch any of a handful of recent action movies that play with time as part of their combat scenes. The slow motion/fast motion trend that 300 used, for instance, would be great for melee oriented Adepts, as would some fight scenes from Crouching Tiger, Hidden Dragon (or any number of similarly modern and elegant kung fu movies). Look at the combat in Watchmen for more, or -- heck! -- even the fight scenes in the recent Batman: Arkham Asylum video game, or parts of Wanted, or Jet Li's The One, or a ton of other Hollywood productions. The Matrix, too, has some excellent examples of how Shadowrun combat could look (particularly the lobby scene, for a pair of cybered-up or Adept-powered Shadowrunners tearing through a standard corpsec team!).
Any time you see the whole world slow down except for one guy who is kicking ass all over the place, you've got some sort of idea of how Wired Reflexes or Move By Wire might make the world look.
