Under the SQL client config program, which normally would have in the connect string:

IP of SQL Server, port (ie 190.555.55.55,1433, 1433 being the default SQL Server port.)

Change that information to the internal IP of your proxy server:

For example:

192.168.000.001,7777

Then add Port 7777 IN to port 1433 OUT to the TCP/IP map in SpoonProxy:

at the IP of your SQL Server.