I've repaired similar with Tape. Though it depends on the material. I think my domes were some type of plastic (or plastic coated). I started with masking tape, then moved to clear package tape, then ended up with fiberglass re-enforced packing tape.
You have to work gently so as not to damage the dome.
Some people say Vacuum Cleaners, but that seems very dangerous to me. There is a change you could suck the Dome right off the driver.
Some say - give it a kiss - and by that they mean, put your mouth on the dome and suck in the hope that the suction will pull the dome out.
I have heard of people using a pin, or dowel, or something similar and small, and putting a drop of Hot-Melt Glue Plastic glue on it and sticking it to the dome. When it sets, which is very quickly, use the peg or pin to pull the dent out. Once you've done the best you can, heat the Hot-Melt Glue with a hair drier or similar until it releases.
I've personally had good luck using various types of Tape.
Steve/bluewizard