Hi!
First, you will need to trick a few parameters.
#define EXTRUDERS 1 -> 2
#define TEMP_SENSOR_1 0 -> I'm not exactly sure about this parameter, but I would choose a sensor that would give you a flat reading since you don't need it. You can manually add a thermistor table with fixed values.
#define HEATER_1_MINTEMP 5 -> Change it to a value below your custom thermistor table.
Comment #define PREVENT_DANGEROUS_EXTRUDE so you printer can extrude at any temperature.
It might be a good start to extrude. Keep us informed on your developments!
DYZE DESIGN
Hotends, Extruders, Liquid Cooling and Accessories.