Can't use a saved-search with Microsoft 'Photos' screenSaver?

I have thousands of photos. I'd like the Photos screenSaver to display from
a SUBSET of those -- a perfect application for a saved-search, no? So I
defined a saved-search that isolates the subset of photos I want (that
worked), and then opened Photos to point it at that saved-search folder --
but (gasp!) Photos doesn't seem to accept or see saved-searches!!

How do I get Photos screensaver to use a saved-search result as its input?

(Photos screenSaver is shipped with Vista, at Control
Panel->Personalization->Screen Saver, then select 'Photos' and press
'Settings', 'Browse')

I'm using Home Premium

I can't use Photo Gallery for this (the query language isn't rich enough),
and wouldn't want to -- this is a PERFECT application for a saved-search.