There are several ways of changing that message, one by changing the DisplayUUTInformationDialog function call inside modelsupport2.dll, or by overriding PreUUT callback, where you could use instead that function call, a message popup, that can be customized to fit your requirements.
After the message popup step, you have to update the Parameters.UUT.SerialNumber and Parameters.ContinueTesting variables inside the callback.
Another way of doing this is to change in the SequentialModel, the PreUUT callback, but this will impact on all the sequence files that are using that model file.