I overhauled my Campag record road hub and it looks exactly the same from that angle so I am assuming that they're similar. If they are then you can just pob the cap off with a screwdriver at the edge or something softer in the axle hole. The little hole in the dust cap is to allow extra grease out when you pump new grease into the middle of the hub.
Originally Posted by fixedpip
Just use a q-tip to clean behind them.
The only problem with this is that it is damn hard to get a q tip into the right place. The dust cap has a u shaped channel on the inside that gets nicely filled with old grease. You would need a set of dentist's tools to clean it properly without taking it off the hub. If the hub has relatively clean grease on the races you could leave the dustcap on and reassemble the hub before pumping it full of grease from the middle (assuming it has the little grease port covered by a clip).