I don't have any real 'technical' write-ups on the ISO, but I'll do my best at describing what I shoot and teach - there are almost as many variations on the stance as there are people out there
Feet about shoulder width apart, squared to the target. Some bend to the knees. I tell my students to imagine they're going to shoot some foul shots on the basketball court or something. One of the great things about the ISO is that the lower body position is almost irrelevant, so assume whatever lower body position makes you most comfortable or is most applicable to your current environment. The same can be said for your arms: some people completely lock out their elbows, some have a slight bend, some like a pronounced bend. Use whatever works best for you, whatever feels most comfortable - but try everything before settling on one position.
Square your shoulders to the target, try to keep them down in their sockets and not hunched up. Bring the gun up to your eyes, not your head down to the gun. If I'm teaching a defensive-oriented class, I ask people to assume a bit more of an aggressive forward lean and a little more hunch to the shoulders and hunch down to the headd, more for mind-set sake than anything; for sport shooting, you really want to be completely relaxed, head up, almost standing straight up. Weight on the balls of your feet, but not leaning forward more than feels comfortable.
Grip is strong-hand high on the gun, strong-hand thumb high on the frame (riding on the safety if you have one there). Support hand very high on the gun (nobody gets this right at first. get it waaay up there), support hand thumb pointed straight out at the target, not touching the gun - just floating in air. Your support-hand wrist should have a pronounced downward cant to it so you can get your fingers under the trigger guard. If you open the fingers of your support hand, they should point out at almost a 45-degree angle towards the ground. Fill in all the space on the support-side grip with your support hand plam as much as possible and as high as possible. Really surround the gun with the meat of your hands. It should look like the gun is disappearing in your grip, with just enough room for the slide to cycle out to the back. If you can see any part of the grip/frame, it should be at the bottom, not the top or the middle. Your grip should be high enough with both hands that the bottom of the grip might well be sticking out of the bottom of your hands.
When shooting one-handed, either strong- or support- many people blade away from the target at 45-degrees or so. I used to do this, but lately I have been getting great results by just staying in the normal squared-off stance and just removing the unused hand (bringing it in tight to the chest). Much more comfortable and feels more aggressive and controllable.
There is no pressure in the hands in a good ISO grip. No 'push-pull' or any of that nonsense. Some grip more with the support hand than the strong hand, I grip 50/50. What you
don't want to be doing is gripping more with the strong hand. Go 50/50 or tighten up the support hand and losen the strong hand. The goals are: repeatability, being as neutral as possiblea and maintaining trigger finger control.
Don't muscle the gun. Don't fight the recoil. Allow the gun to recoil almost freely, without any extra effort on your part to control it. With a good neutral grip and a good index, the gun will return
on its own to the target with out being pushed there faster than you could get it back if you tried. If you over-muscle the gun, you'll find it not returning to the target properly. You'll be re-adjusting for each shot as the muscle tension moves the gun to wherever your muscles push it - and it's not going to be back on target, it'll be off by whatever amount your grip is imperfect. If you're squeezing a hair more with your left hand this shot than you were, the gun will be off because of it. The more neutral you can keep your grip, the more the gun will function like a machine in a rest - recoiling back to it's starting position each time, ready for the next shot with little or no adjustment on your part.
Always keep your head/gun and hips moving together as a unit as much as possible, working as one - like a turret on a tank. Turn your body from the hips to your next target, pushing yourself around with your knees and legs. That upper body working as a single unit (head/torso/gun - especially head/shoulders/gun) is what provides your index, it's what keeps the firing platform consistent from shot to shot and allows you to shoot with your vision. You see something you want to hit, you turn to face it and the gun is right there. You can shoot anything you can see as fast as you can turn to face it.
That's all for now.
Hope this helps,
- Gabe