VSS is a Microsoft product and has no Java API. It does have a command line tool called ss.exe which you can call with a ProcessBuilder. Check the help files that come with VSS to see what the command whould be.
The Apache Ant tool ships with tasks that integrate with VSS, so you could either run a suitable Ant build file programmatically, or rip out the code that accesses VSS and use that in your code. It most likely uses Runtime.exec or ProcessBuilder internally.