specify completely different theme for one page?

Does anyone know of a way or plugin (or hack) to allow specifying a completely other theme (folder) for just one or two of the pages on a blog? I basically want my blog pages to look and work one way (that I already have a theme for) and the pages look and work another (that I also already have a separate theme for). I don’t want to have to merge these and create template pages. I just want the blog to use one theme for some pages, and a completely other theme for other pages. These two themes each live in their own named folder under the themes folder.

Any ideas?

Thanks very much in advance for any help.