Well, unfortunately Arnie died and Infinity doesn’t have anyone left that knows much about speakers and nothing about the IRS. A very different company now, just a pale shadow of what they once were.
You want the panels to be about 80% as wide as you are seated back. So, for example, if you’re seated 12 feet from the panels, you’ll want to start with the panels about 9.6 feet apart as measured from center to center of the panels and then tweak them from there.
The IRS appreciates the Rule of thirds in most rooms so I’d start with the panels about 10 feet from the front wall. You’ll likely want some diffusion panels like RPG on that front wall as well.
The woofers are a b*tch to place because they’re about 300 pounds each and not a lot of fun to move. Most IRS have the towers to the outside of the wings. Mine, for example, were outside enough that in my listening position I could see half of the woofers, while the other half hid behind the wings. In later iterations, Chris moved them more together so I can no longer see them. The trick is to find where you’re going to be sitting based on imaging, then move the bass towers until you find the most even bass response in your seated position.
You might also consider doing what we did, replacing the crossovers. They almost always need replacing. Our Chief Engineer will build you new crossovers if you want.
Good luck!