I don't have a visible six-pack at the moment, but I have gone down to <10% body fat a couple of times to get my veins and abs to show.
For me, it's basically all diet. Protein, vegetables and water. No juices, fruits, breads, pastas... I'll usually drop 2 pounds a week, consistently. Of course I'm a damn grouch when I'm dieting, and don't even think about eating potato chips in front of me or I'll go into a jealous rage
The women in the gym I go to have insanely gorgeous bodies... and I've never seen them workout with much intensity. It's a light session on the elliptical, some resistance exercises with very little weight, and that's it. They must eat like birds
I've never done abwork consistently, as I can barely eke out 30 situps before I get crampy. Abwork definitely not needed for a six-pack. Diet, diet, diet!