You really just need to get a connection to the SQL Server from your Unix box. A quick search for SQL Server Linux Client got me to http://richbs.org/post/43142767072/connecting-to-microsoft-sql-server-from-unix-linux-mac

That page will go all the way through getting access with Python, but if you follow the instructions down to getting isql up and running, you should get to where you want to be. With isql, you can connect to your box and enter your exec statement to run your stored procedure.