Hi,
For each field in context node there will be GET_I method.
If the method is not generated then right click and select GENERATE GETTER and SETTER METHODS.
After that GET_I_(FIELD NAME) method will be GENERATED.
Put only below code to disable the fields.
RV_DISABLED = 'TRUE'.
This will disable the field even if the entity is in change.
Regards,
Naresh