fill sc_task variables via ATF

Hi,

i want to fill field values in the sc_task with the ATF, f.e. in the Screen you can see the red variables. How i can fill them (without a script in the ATF) ? By using the OOTB "Set Field Values" i won't find the field "Servername", i also try dot-walking and don't find the "variable" Section. Maybe someone has a working "ATF Step Configuration" for "Set Field Values (Task)" ? Or any Solution ?

Thanks in front

Jochen