The drivers side is harder, but a combination of a allen socket and a regular allen wrench will get it done. I think you can do all four from above. As was mentioned, clean-out the heads of those bolts very well. The one closest to the engine on the driver's side is the worst 'cause you can't see it. A tip is to dip the end of your socket/wrench in Ajax to get the surest grip. It would be a good idea to use some never-seize on the bolts on reassembly in case you have to do it again.

In case you live long enough.