LabVIEW can create dll's if you have the Application Builder, but you
would have to know the exact structure of the plug ins in order to get
it to work. As far as I know Pro Tools has two different audio drivers
that you have to support and I am not entirely sure they use dll's for
the plug ins. I would suggest contacting DigiDesign to see how to
create you own plug ins.
Regards
Jon B
Applications Engineer
NIUK