If you leave the switch in the ON position (always) then it will always start up when you plug it in. There's no API or GUI control for power on/off.  The web admin allows for restarting only. Here is one suggestion that you may use is the controllable power devices, such as

Please keep in mind these devices from amazon are third party devices. It is the user's responsibility if anything goes wrong by using these devices. 

Note: ThinkRF D4000/R5550/R5750 uses the non-momentary switch.

Keywords: Power Switch, remote control.