How to send command directly to the FMU with the CLI desactivated?

Hello guys,
I’m building a quadcopter using an Holybro Pixhawk4-Mini updated with the Ardcucopter-ph4-mini-v4.0.7.
I was trying to change the I2C speed bus because i’m using specific sensors and i would like to reduce the speed of readings to see if the signal become more stable.
I saw some topics about sending a command of type “fmu i2c busId freqHz”
But now with the CLI desactivated how can i do it ?

Thanks for you help