... or how I learned to stop worrying and just write code against completely undocumented APIs from Microsoft. Is there any actual documentation of the official
Have you tried deriving from (StyleBundle or ScriptBundle), adding no inclusions in your constructor and then overriding
public override IEnumerable EnumerateFiles(BundleContext context)
I do this for dynamic style sheets and EnumerateFiles gets called on every request. It's probably not the greatest solution but it works.