Manipulate SCORM 2004 Data Model Elements

For anyone interested in overriding a calculated score, or prepending/appending text to freeform interactions/responses, as of Storyline v3.74.X, they are still including scormdriver.js in the published 2004 packages which includes a function called SCORM2004_CallSetValue
With that function, and a submitting results on timeline start (that's key), you should be able to nullify any calculated score – on the first attempt of the course. Resuming a course would likely involve adding conditions to your triggers?
I used this function to prepend some text to freeform interactions (see the trigger on Final Slide button).
SCORM2004_CallSetValue('cmi.interactions.0.learner_response', newTxt1);

This has been verified in SCORM Cloud. Just inspect the Debug Log they generate to determine the element (cmi...) you need to control.