I did this in my town. It was a local theater though, not a big chain

• Went on a Wednesday night and rented access to a screening room for ~5h. We had to pay extra because they normally close earlier on a weeknight
• Showed up early to meet the projectionist and get a technical rundown
• Setup was a friend's laptop plugged into HDMI running up to the projector booth
• Nobody complained when we brought out a disk full of torrented movies
• The theater already had a license to sell alcohol, so we had that covered
• We brought a small bit of outside food, and nobody complained

It was absolutely the best time I ever had at a cinema. When the evening wound down, the projectionist invited us into the back area for a tour of the projection equipment.

I think that because we were a private event the rules about screening copyrighted materials to public audiences did not apply.