There are a number of packages that will work with LabVIEW if you want to integrate the source code control program with LabVIEW. Perforce will work, as will Microsoft's Visual SourceSafe and CVS (a free one). I've heard that Subversion (a variant of CVS) works as well. Just in terms of operational compatibility with LabVIEW any of these will work. The real question isn't what will work, but rather what you configuration management process is, and what your software development process is. That, more than anything else, will dictate which tool fits your needs.