In theory just replace all SQL commands having geometry:: cast to geography casts (assuming that you 2008 R2 MSSQL server) Edit: looked that example code . Change Microsoft.SqlServer.Types.SqlGeometry to Microsoft.SqlServer.Types.SqlGeography OR Find SQL command which select code and force it to cast your geography objects to geometry
Just off the top of my head in SQLServer,
You can query the geography data type using: .ToString () See http://msdn.microsoft.com/en-us/library/bb933803.aspx for the reference info.
Then you'll just have a long and lat floats which you can send to json.