Why do you need to attach it to something?* Is the screen too flimsy for the weight of a dome light + bulb? I use welded wire tops on my tanks, they support the weight
of my (aluminum-) domed warming lights. (*I'm assuming you don't have a curious cat or kids on the loose that might knock it off? That would be unsafe any which way...)
Might help to see exactly what you're talking about...in case I'm misunderstanding? I've seen dome lights that come with a pinch-type clamp but I just take it off & don't use them. Scratch that, I just looked them up, & I have some just like them...& yeah, I removed the clamps because obviously they cannot hang onto the edge of the tank if you need a lid on it to keep a snake in. I'm sure you could devise a work-around to attach it if you feel you need to though. I suppose it would be safer...in case you have an earthquake, you don't have a hot lamp fall on your flammable carpet, etc.