Is it possible to flash a DSG ECU with manual software or will I need to source a manual ECU?
Sometimes the hardware is a the same. sometimes not. It can't be coded, but *may* be able to be flashed.
On my Touran (MK5 based) I ended up buying a new manual ECU. Flashing the manual file onto the DSG ECU didn't work for me, but I needed another ECU anyway, as mine had some damage I'd repaired temporarily.