You can't force ecu to code something that doesen't exist in flash. If it won't accept coding that is it. You can't do anything more.
just so there's not just useless replies like your first one and this one as well, here is how i solved this a year later and never got around to posting it.
The eeprom was corrupted, my flash contained a manual file (tuned file for that exact car) and only the eeprom was coded as an automatic, so your comment saying it doesn't accept coding of something that doesn't exist in flash is funny, I actually checked the VARDEF with WinOLS and my file was as correct as it could be.
Looking back, maybe the coding wasn't being accepted via VCDS, because of the current EEPROM coding not being stored in the VARTAB of the flash.
I did read the eeprom with VAG Commander and made the necessary changes to the file, including changing the VIN because it was from some B6, but couldn't write it back through OBD and I wasn't so good with electronics back then to write to it directly.
Flashing the ori file or reflashing my tune through obd didn't do anything to the eeprom and it stayed coded as an automatic...
...but when I crossflashed a file from a different ECU (TT180 afaik), the eeprom edited itself to the its coding (of the TT file), which was still wrong for my car, however, flashing my tune back finally edited the eeprom back to the correct coding.
This is apparently the easiest way to get this done in this exact situation I was in, if you don't want to open up your ECU or get into boot mode.