You can use the "all" keyword provided that it's specified within a file. I strongly recommend doing a dry run first in preview mode and check for any errors, depedencies, etc, eg:
echo all > /tmp/a
installp -rpf /tmp/a
then if all is OK run
installp -rf /tmp/a
I don't know what AIX version you're running but I have found that when attempting to reject lots of filesets (such as complete maintenance levels) in later versions of AIX invariably result in lots of filesets being left in a broken state. Make sure you take a mksysb and any other backups first!!!
Hope this helps...
Joe