Hi Martin,
The "Motor Gear Ratio" is the ratio of the large pulley to the small pulley. So in your case this is 40:20 = 2:1, so enter 2 in the box.
The "Worm Gear Ratio" for an EQ5 is 144, so that stays the same.
The "Motor Step Angle" will be 0.9 for you as your motors are 0.9 degrees step angle.
"Axis Reverse" may have to be enabled. The only way to tell is once you run it, if you find the motors are going in the wrong direction (e.g. when sidereal tracking is enabled the stars move twice as fast), then you'll need to run the config utility again and click on the axis reverse button so it says 'on'. Depending on your wiring you may need both on, both off, or one on one off. Trial and error here.
Once the settings are entered, click update for each axis to calculate the correct ratios. When you are done, you can use the 'save' button to save the configuration to a file (in case you want to change it later), and the 'done' button to upload the settings to the EEPROM.
Regards,
Tom.