Invoke AppleScript from Outlook
You can use the AppleScript menu on the Menu bar. Script Editor > Preferences... > General


Script Menu: [√] Show Script menu in menu bar


Place your scripts in: ~/Library/Scripts



Or create Automator Service workflows using a Run AppleScript action.


Automator > New > Service
Service receives selected no input in any application
Add a Run AppleScript action
Replace the default AppleScript code with you code.
Save the Service workflow. (They are automatically saved in: ~/Library/Services) 


You can now access them from the Services menu in Outlook.

You can also assign a keyboard shortcut to any Service workflow that might be relevant to have one. This is done in: System Preferences > Keyboard > Shortcuts > Services

Or use a third-party utility like FastScripts.