If the touchpad is detected correctly, the synaptics driver shold be autoloaded. Check it with the following command:
cat /var/log/Xorg.0.log | grep -i synaptics
A positive output would look something like this:
~$ cat /var/log/Xorg.0.log | grep synaptics
[ 32.848] (II) LoadModule: "synaptics"
[ 32.849] (II) Loading /usr/lib/xorg/modules/input/synaptics_drv.so
[ 33.096] (II) Module synaptics: vendor="X.Org Foundation"
[ 33.097] (II) Using input driver 'synaptics' for 'ETPS/2 Elantech Touchpad'
[ 33.097] (II) Loading /usr/lib/xorg/modules/input/synaptics_drv.so
[ 33.160] (II) synaptics: ETPS/2 Elantech Touchpad: ignoring touch events for semi-multitouch device
[ 33.160] (--) synaptics: ETPS/2 Elantech Touchpad: x-axis range 0 - 1152
[ 33.160] (--) synaptics: ETPS/2 Elantech Touchpad: y-axis range 0 - 768
[ 33.160] (--) synaptics: ETPS/2 Elantech Touchpad: pressure range 0 - 255
[ 33.160] (--) synaptics: ETPS/2 Elantech Touchpad: finger width range 0 - 15
[ 33.160] (--) synaptics: ETPS/2 Elantech Touchpad: buttons: left right double triple
[ 33.160] (--) synaptics: ETPS/2 Elantech Touchpad: Vendor 0x2 Product 0xe
[ 33.161] (--) synaptics: ETPS/2 Elantech Touchpad: touchpad found
[ 33.189] (**) synaptics: ETPS/2 Elantech Touchpad: (accel) MinSpeed is now constant deceleration 2.5
[ 33.190] (**) synaptics: ETPS/2 Elantech Touchpad: MaxSpeed is now 1.75
[ 33.190] (**) synaptics: ETPS/2 Elantech Touchpad: AccelFactor is now 0.145
[ 33.192] (--) synaptics: ETPS/2 Elantech Touchpad: touchpad found
[ 18442.841] (--) synaptics: ETPS/2 Elantech Touchpad: touchpad found
If that's what you get, try turning on horizontal scrolling with
synclient HorizEdgeScroll=1