Custom facet.sort

Hey guys, I have a desire to order (field) facets by their order of appearance in the search results. When I first thought about it, I figured there would be some way to plug a custom Comparator into FacetComponent and link it to facet.sort=rank or something like that, but not only is there no

custom facet.sort

Is it possible to plug in a custom java class to provide custom facet.sort modes? Thank you Giovanni