Here is a blog entry that describes how to enable an OST on Outlook 2003
http://davidoverton.com/blogs/doverton/archive/2007/07/28/how-to-enable-cached-mode-for-outlook-when-used-inside-terminal-server-which-means-that-bcm-can-work-too.aspx
OK, this is in response to the people who have posted on this subject.
Someone was kind enough to give me the exact details, but I shall
protect my sources except to say they know the insides of MS tools
well.
The warning here is that this is unsupported and could completely
destroy your users profiles, so only do this is you are comfortable
editing the registry
The short description:
Open up Regedit
navigate to [HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows
Messaging
Subsystem\Profiles\\13dbb0c8aa05101a9bb000aa002fc45a]

Find the key 00036601 (REG_BINARY) - note the number in it now so
you can undo the changes if needed
Change the value to one of the following
•enabled value; 84 01 00 00 - note that on my desktop system the
enabled value is 84 19 00 00, so play around with this a little
•enabled with Public Folders/Favorites: 84 05 00 00 •disabled value;
04 00 00 00

FYI - you will need to search for "00036601" and adjust ALL of them
since each key is for a different user on your system.