2 - Flashes (prferably speedlights for portability)
2 - Stands (either tripods or light stands)
3 - Pocket Wizards
2 - Sync cords
The Q-flash up on a light stand. Although it is bigger then a speedlight it is considerably more portable then studio strobes.
All of the images were shot at ISO 800 with a Canon 1d MkIIn with a 70-200mm 2.8 lens. The exposure was 1/250th at f-3.5. Both flashes were set to 1/4 power, had i turned up the power of the flashes i could have shot at ISO 200 with the same exposure. However i keep the power at a 1/4 to help recycle time, battery life, and for a faster flash duration (specifically on the q-flash). Both lights are pointed at the top of the 3-point line and on speedlights in which you can set a zoom, i generally set that to 35mm.