It appears however, that it's not possible to write the ECU in bootmode using this feature. I have at least not had any luck with it.
Step 1: Open the ECU
I did this carefully with a screwdriver
Step 2: Locate the 29f400 chip
This is where the flash is stored
Step 3: Fire up FGtech galletto v54 and go to Tools Boot Mode > Siemens-Infineon C167 > Bosch ME7 - 1 Micro - Flash 400 Boot Mode
Step 4: Connect the ECU like this without putting on power yet (On my pictures i have made an EDC15 to OBD adapter, but basically the same):
Step 5: Press Read ECU now follow the instructions (Put ground on pin 24 of the flash > Apply power > Remove ground after approx. 5 seconds)
All gone well Galletto 4 should now read the flash.
All gone well Galletto 4 should now read the flash.
Hope it helps.