I made a simple synaptics-toggle script:
if [ -f /tmp/synaptics-touchpadoff ]
then
synclient TouchPadOff=0;
rm /tmp/synaptics-touchpadoff;
else
synclient TouchPadOff=1;
touch /tmp/synaptics-touchpadoff;
fi
and mapped the script to XFCE keyboard binding utility.
Upon finding ArchLinux more elegant solution here, I had to admit I was a bit ashamed.