Taken from: http://blogs.msdn.com/astebner/archive/2006/07/24/677497.aspx

Visual SourceSafe 2005 uses the same setup.exe wrapper and same installation logic as the Visual Studio 2005 family of products. As a result, you can use the same techniques to deploy Visual SourceSafe 2005 or perform an unattended installation. In particular, the following topics will probably be most useful to you:

How to create an administrative install point and install using Group Policy

How to suppress reboots during unattended install

Enterprise network deployment readme (this document specifically talks about Visual Studio 2005 but the topics apply equally to Visual SourceSafe 2005)

How can I suppress reboots during Visual Studio 2005 unattended installation?