I'd like to disable hardware buttons on the synaptic touchpad, but still be able to use the touchpad and "tap"-click on its surface. I don't find the related options in the output of synclient -l.
Note that I don't want to disable the touchpad completely. Only to make it ignore the hardware buttons, but still respond to taps.
Disabling Touchpad:
Press Alt+F2 and type gconf-editor and click Run.
Navigate to desktop>gnome>peripherals>touchpad,in the right panel uncheck the entry touchpad_enabled.
Now your touchpad will be disabled.
To turn off touchpad completely install gpointing-device-settings 
. After installation you can access it under System > Preferences > Touchpad
UPDATE:
If you want to use synclient then you have to edit your xorg.conf file.
sudo -H gedit /etc/X11/xorg.conf`
This will disable the hardware buttons and the "tap" feature, but you will be able to move the pointer:
1) Create this file:
gedit ~/.Xmodmap
2) Paste this into it:
pointer = 0 0 0
3) Logout and log back in, or reboot, or run this:
xmodmap ~/.Xmodmap
To get it back to normal:
1) Edit the file:
gedit ~/.Xmodmap
2) And change to:
pointer = default
3) Logout and log back in, or reboot, or run this:
xmodmap ~/.Xmodmap
4) If this file doesn't have anything else, then you can delete it after step "3":
rm ~/.Xmodmap
