Refine search through a button

In a button, how would I go about to search some folders, then refine said search?

I have a very huge icon library (commercial) which has several imageformats and whatnot, but I'm
trying to limit the time I wade through the library each time I want some kind of icon, hence the
first search would be, limiting the file formats and whatnot (this one is in a search filter), but the
second search (refining) should be done by the user.

It would be nice if I could somehow get to the point where "refine search" is checked, by clicking said button.

Probably easier to do it the other way around. Do the special search you want, then filter by extension. You can set up buttons to filter by extension, or use the filter bar's drop-down list. (* key opens the filter bar by default.)