Hello,
Software updates for the DSG (direct-shift gearbox), meaning flashing new software onto it, cannot be done via VCDS. Regardless, where would you even obtain the new DSG firmware?
Possibly, something could be done via
J2534 and the Offboard Diagnostic Information System Service - diagnostic software (ODIS), but that would need to be checked: See
http://erwin.volkswagen.de.
Why do you want to update the DSG software? What problems do you think it has? And what specific issues would the DSG update firmware that's compatible with your vehicle fix? Do you have any idea? Okay, question answered...
As long as everything is working as it should, I would limit maintenance work on the DSG transmission to routine servicing, such as oil changes for "wet" DSG transmissions.
Best regards, Rainer.