Setup "ARM" in SITL Mode

I want to get actuator_outputs while doing SITL.
The problem is that if the vehicle is not armed, then commander doesn’t publish “actuator_armed” topic, therefore pwm_out_sim doesn’t publish “actuator_outputs” topic, and finally therefore simulator_mavlink doesn’t send actuator_outputs.

But simulator_mavlink currently accepts only MAVLINK_MSG_ID_HIL_STATE_QUATERNION,
MAVLINK_MSG_ID_RC_CHANNELS, MAVLINK_MSG_ID_HIL_GPS, MAVLINK_MSG_ID_DISTANCE_SENSOR,
MAVLINK_MSG_ID_HIL_OPTICAL_FLOW, MAVLINK_MSG_ID_HIL_SENSOR messages.
So i can’t setup armed state by sending custom command.

Could please anybody explain how to enable armed state for the vehicle in SITL?