File and folder referencing from within a bundle

Hi,
I am creating a bundle for an MSI and there is a command line parameter for an additional folder , e.g dfl="c:\update folder" . I can create the bundle and have it cache the install files within the bundle (including the update folder) but how do I reference the update folder in the bundle ? I have a workaround by installing the folder to the local machine and referencing it but there must I think be a way to reference files and folders copied to the server as part of the MSI bundle. ie fdl=".\update folder" ? Can anyone advise ?

Grey