Classes not found

I'm working on backporting a few modules (facetapi_select/multiselect) to 6.x, but I'm constantly running into Class not found errors, because the 6.x-3.x version of FacetAPI doesn't provide any auto-loading of classes on it's own. It works fine for FacetAPI itself because it takes care of loading classes where necessary. But contrib modules seem to be outta luck.

For now, I'm putting a few if (!class_exists(...)) in my modules, but I think it's ultimately the responsibility of FacetAPI to include it's classes globally.

Obviously that's not "cool", because it means loading extra code, but since D6 doesn't have lazy-loading classes, it seems it's the only option.

Thoughts? I'd be happy to provide a patch, but I'm curious to hear ideas on the matter.