How do I make my touchpad disabled when mouse plugged in, but able to turn it on by Fn+F6?

Hello all, I have a laptop Lenovo G580. My problem with it is Synaptics Touchpad. Every time when I power on my laptop I need to press Fn+F6 to disable touchpad. I can create udev rule that will disable touchpad if mouse is plugged, but if I do so, I can't enable touchpad by Fn+F6. How do I do this?
UPD. With synclient, I can change TouchPadOff setting, but it does nothing, using xinput --enable|disable I can enable or disable touchpad (but Synaptics Off property keeps unchanged, it also unchanged with Fn+F6).