Here is a post that talks about how to do this:
http://gblsharepoint.blogspot.com/2013/01/using-wspbuilder-with-visual-studio-2012.html
Note the path in Win 2008 R2 is: C:\ProgramData\Microsoft\MSEnvShared\Addins
http://gblsharepoint.blogspot.com/2013/01/using-wspbuilder-with-visual-studio-2012.html
Note the path in Win 2008 R2 is: C:\ProgramData\Microsoft\MSEnvShared\Addins