How can I reference TARGETDIR in an installer class?

[PJRoyle]

I have an app which needs to do some custom processing in the installer, so I have included a Custom Action and an Installer Class, with the CustomActionData set to /From=ADir /To=Bdir, where ADir exists and I want BDir to be the application's installation folder under Program Files. I can hard code this second value fine, even with spaces in it (by putting it in quotes) but I can not get it to use [TARGETDIR], which is, as far as I can see, the property for the application folder. This means I have to hard-code the installation folder and suppress the Installation Folder dialogue.

Is there a way to do this? Preferably not involving prestidigitation, rabbits out of hats or superstring theory?

Thanks,
Peter Royle