WHOA! I read your post incorrectly and missed the part about the joists being light gauge steel. I hate those darn things!
We rarely see them around here so I don't have the boring allowances committed to memory but I'm thinking that you cannot do much more than you can do to wood to them, if anything at all. There is a manufacturers association for light gauge steel framing member manufacturers and I'm betting they have their prescriptive methods for cutting holes posted online. Can't think of their name off the top of my head unfortunately. The last time I inspected them in a home, the manufacturer did not allow any cutting of holes, as there was a fairly large rolled opening every three or four feet.