I have about 400 romsets in my collection. How do I use clrmamepro to make sure that I have a screen snapshot for each romset, but that I don't bother with snapshots for romsets that I don't have?

I see how I can download a MAME32 Snaps datfile from clrmame.com, but I don't see how to tie it to my romset collection - that datfile wants to make sure I have every possible snapshot, without caring if I don't have the romset in question.