Once again we have a post that asks questions with out giving detail as to what the poster is talking about .If we are talking double guns then what you ask is not a practical as a rolled edged guard is made when the guard is filed up from its forging or construction. An earlier post have suggested a solution but personally I think this would look very strange .
The average guard in finished state is not heavy enough to do much to ,although some lower grade guns do tend to have thicker bows so it may just be possible to form some sort of bead .
With modern welding it should be feasible to have a bead welded to the guard that can then be filed up to the correct profile .
It will depend on the gun and why you want it and how you want it to look when finished .
However to answer your original question , files and some ability are all you need .
