Audio Drivers on Windows XP Embedded

This question has been asked by many people on the Win XPe newsgroup and no
one has been able to come up with an answer, so I'm hoping someone here may
have a suggestion.

When installing drivers on Windows XP Embedded the installers often ask for
the path to some files which are already on the system and it is necessary to
manually browse to them. This is most common with audio drivers which ask for
the location of ks.sys and ksuser.dll.

I have tried making sure \System32 and \System32\Drivers are added to the path
environment variable before launching the installer, but this doesn't help.

Does anyone have any knowledge of how these installers typically try to find
required files and any idea how I might be able to let the installers know
where they are?

--
- Mike