Microsoft Outlook Calendar

I am looking for the easiest way to customize the Outlook Calendar appointment form to include a couple additional “show as” options (i.e. vacation or comment)in addition to those already included such as busy, out-of-office, free, tentative.

I realize that we could use the out-of-office option for vacations and show text as such, or use categories, but not all users have the same coloring for their catergories and we are trying to use as a office-wide calendering system that is consistent and easy to interpret.

Any help is greatly appreciated.