tried what you suggested with lightroom....had to choose Other (there was no installer from dropdown). navigated through system/library/but there were no CoreServices listed.
tried same approach with iwork, but there was no "Open With" panel in the Get Info window.
When I clicked System Preferences, it gave me this message:
You don’t have permission to change the application for this document only. Do you want to change all similar documents to open with the application “System Preferences”? This change will apply to all documents with extension “.pkg”.
Does this have something to do with my problem? Do I need to change security settings or create a new Admininstrator?