You can add the command to your startup applications: Dash > "Startup Applications" > Add the command:
/bin/bash -c "sleep 15&&synclient VertScrollDelta=-120 && synclient HorizScrollDelta=-120"
The break of 15 seconds is to allow the desktop to load before the settings to change (else the command would break).
On next login, it should work (after 15 seconds). You can experiment a bit with the break. Probably the 15 seconds is on the save side.
Alternatively
You can (in general) create an autostart item manually (which gives you full control)
[Desktop Entry]
Name=Touchpad settings
Exec=/bin/bash -c "sleep 15&&synclient VertScrollDelta=-120 && synclient HorizScrollDelta=-120"
Type=Application
Copy the code above, paste in into an empty file and save it as:
settings_touchpad.desktop
In ~/.config/autostart. On next login the command in the Exec= line will be executed.