This will create symbolic links within the source tree becaus CVS does not deal with symbolic links. It will also release all of your local copies of the sif libraries and replace the directories with links to the library source trees in the shared UG area. This will save space and time by not forcing everyone to maintain copies of the libraries. This will give you a local editable copy of the library. That is all you need to do to start.
All libraries start out as being shared.
The sif.tar only has symbolic link place holders. This is your copy of course.