i haven't option something like "disable usb download".
In SDM, I call it 'Disable USB Download' because that is what it does .. it prevents the camera going into image-download mode when connected to the PC in playback mode.
AllBest calls it 'Enable remote(USB)', which means allow the use of a remote switch.
It is a little confusing but it is the same thing !
You do not need to run a script in ALT mode with SDM.
In ordinary mode, just press-and-release the button.