I'd be curious to know too... I use a floor jack and stands and didn't see any obvious place to use the stands. So I made wooden inserts (see photo) to put on top of the stands to work with the rubber pads.
I should have made them out of hardwood, the 2x4 wood I used compresses if the car is on too long, allowing the side panel of the car to contact the wood.
If I run into someone with a machine shop I'd like to have them cut something similar out of a chunk of aluminum or something, ideally with some side panels welded on to keep them from sliding off. Maybe someone here will manufacture some as a mini business venture?
Or maybe just weld a plate of steel permanently onto the top... hmm... actually I have access to an arc welder and some steel. Anybody see any downside to that? Welding wouldn't weaken the stand or something?