hmmm. Let me try and explain it all out as best as i could. There are some name of the files which i still do not know of.
Basically, the Larger the frets (fret 1 to 12) the harder it is to scallop.
U need files of 2 diff sizes min. I use Half Round files for mine, the smoother one and the one that looks like a durian skin (diamond half round file?)
Draw a line on where u will be hitting the rounded edge. Start off with the corner of it, and start filling away to get the basic cresent moon shape at the corner from one fret to the other.
than do the same for the opposite side. Once u have the rough shape, start filling from the middle, than work progressively to the sides eventually creating the scallop shape.
Now, this is just for your information. Just because your using a really rough file doesnt mean it will makes things faster a lot faster. took me about 7 hours to create those scallops u see in the pic.
Another thing to look out for is to make sure u do not file until u hit the fret. U might loosen the frets in the process which is a NO NO. Thats u see some parts along the frets which i intentionally left alone, and just in case i want to re fret in the future.
If there is any other information, please feel free to ask. I will try my best to answer you.