Here's a quick way to add Directory Service Restore Mode to the boot options menu in Server 2008.  From an elevated command prompt, execute the following commands:

• bcdedit /copy {default} /d "Directory Service Repair Mode"
• bcdedit /set {<GUID for new entry>} safeboot dsrepair

Where <GUID for new entry> can be cut and pasted from the results of the first command executed.  You can control menu timeouts from within System Properties.