Font Size - XP style vs Vista style

I understand what "Use Windows XP style DPI scaling" does. I have it
checked because most programs work fine that way, while turning this off
makes them blurry.

But occasionally, a program will be way too small and/or have layout
problems. What I really want is to use the 96DPI emulation only on the
apps I specify, namely the problematic ones. With the check off, it
uses emulation on everything that doesn't specifically say otherwise in
its manifest, and nobody's done that yet.

To summarize, I want the checkmark on normally, and use the new
Vista-style scaling only when I (not the developer) specify.

How do I do that?

--John