Shannon,
You can do it using NT with no AD by creating a .reg file and importing it with regedit /s in a login script. The /s switch tells regedit to import the settings silently, and not notify the user.
The reg file should look similar to the following (this is for Outlook 2003):
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USERSoftwareMicrosoftOffice11.0OutlookPreferences]
"FBPublishRange"=dword:0000000c
"FBUpdateSecs"=dword:000004b0
FBPublishRange is the number of months to publish, expressed as a hex value. (c = 3 months in the above example)
FBUpdateSecs is how often (in seconds) to update the free/busy information expressed as a hex value. (4b0 = 1200 seconds, or 20 minutes in the above example)