Dynamic default values for parameter groups in postinstall script

I'm playing around with postinstall scripts for a PEAR package and wondered if there are any way of changing the default values for the parameter groups specified in package.xml from the postinstall class. The reason I want to do this is that my first parameter group is an optional existing configuration file (the results of the postinstall script is to write a configuration file). If someone specifies an existing file I would like to override the defaults from package.xml with the values found in the configuration file. Is there any way of doing this? I see that the init method in the postinstall class is passed an instance of PEAR_PackageFile_v2, where the values specified in package.xml exist. I'm not sure if they are meant to be changed though... -- Christer Edvartsen http://cogo.wordpress.com/ http://twitter.com/#!/cogocogo