SSIS Script task enlist in the current transaction

I have a package in SSIS with multiple task. I am loading file,if the Filesystem task at the end fail i want to be able to rollback the transaction.My package look like that. I like to be able to rollback all the operations the SSIS script have been done.To do that i need the SSIS script to enlist in the transaction created by the BEGIN_TRANSACTION Sql task.How could i do that ?

In ssis to gather the transaction i do :

 object rawConnection = Dts.Connections["destination_ado"].AcquireConnection(Dts.Transaction);
             myADONETConnection = (SqlConnection)rawConnection;

Then i do a BulkCopy:

using (SqlBulkCopy sbc = new SqlBulkCopy(myADONETConnection))
                    {
                        sbc.DestinationTableName = "[" + SCHEMA_DESTINATION + "].[" + TABLE_DESTINATION + "]";
                        //  sbc.DestinationTableName = "test_load";
                        // Number of records to be processed in one go
                        sbc.BatchSize = 10000;


                        // Finally write to server
                        sbc.WriteToServer(destination);
                    }
                    myADONETConnection.Close();

How do I tell the SqlBulkCopy to use the existing transaction ? In the options of the connection in SSIS i use RetainSameConnection:true

Thanks for all your thought

Vincent