[Zope] Searching a FieldIndex for prefix or OR

Is it possible to search a catalog on a field index for either a given prefix, or any of a list of values? Maybe I'm going about this wrong; I want to add the ability to only show objects found below a specific place on my site, and to do that I created a field index on the path to each object. Then at query time I would like to search for /foo/bar/*, or failing that create a list of all paths below /foo/bar and create an OR query. The solution I'm using now is to post-process the search results, but that seems lame :) Thanks, -Randy