I have no idea of how to do that without either asking the user where it's installed or getting the path for the executable via a file it is associated with, like using the FindExecutable API.

It is also probably possible that you could find where it's installed by looking at the uninstall info, but this could easily chage from version to version aswell.

Or you could search the first time you need the filename and path and then rember where it was the next time, you have a lot of options here.