You should be able to use netsh command and use the firewal option to open the port 1433 for SQL Server.

netsh firewall set portopening TCP 1433 "SQLServer"

Refer the below links

http://support.microsoft.com/kb/968872

http://blogs.msdn.com/b/jorgepc/archive/2009/08/25/open-firewall-ports-for-sql-server-the-easy-way.aspx

http://support.microsoft.com/kb/839980