I don't think you'll be able to use the 'SQL Data' even to upload this because this template creates a straight SQL statement under the covers (you can view it by clicking "Edit Code" for this event). As I understand it in ADO.NET, binary data must be inserted via parameters.Â
You could write the parameterized ADO.NET code within a Server Event. The ADO.NET would expect a byte array (bytey]), which is the actual binary data. This can be retrieved via the below call (where "EmbeddedFile" is the binary process data field).
 byte ] oBuf = (System.Byte.]) K2.ProcessInstance.DataFieldsi"EmbeddedFile"].Value;
At this point it you can write normal ADO.NET code within the server event to insert the binary data. There are a number of examples on the internet that show how to insert Binary data into SQL via ADO.NET via the use of a paramertized query.
You will not be able to do it using SQL Data event. Use Server Event with custom code instead, where just put bytes from your binary field manually.