installer feature 'wizard'

Hi, is there a possibility with the pear installer to define a script in package.xml that will be run/included by the installer _after_ install of a certain package was 'ok' and maybe also another one that is called _before_ a package is uninstalled? If not, wouldn't it be a nice feature? I found it useful if packages need further settings/installation, e.g. if some scripts have to be copied into a web dir or if a database / some tables must be created or modified, or if it is necessary to change some file/dir permissions or to create a dir and so on - I guess you'll find some more examples ;-) Regards, Matthias