I think that while there are some functions that can be accessed and changed with the Mini VCI there are others, like the ambient temp function that need the MUT3 to download a .kon file from the relevant computer module, alter the file using the Etacsdecoder software, then upload the altered file back to the module,again using the MUT3.
I have changed functions like the door unlock feature without using a .kon file download/upload... but stuff like Cruise Control and the Ambient Temp function will, unfortunately, need a MUT3.