The concept is more or less the other way round. The filament pulls the syringe and squeeze the material out.
for more images and movies, see http://www.facebook.com/europerminutedesign

Resize the shapes suited for your syringe.
Print the syringe holder.
Print the end stop enlargers.
Screw same [ultimaker spare] m3 bolts through the holes to fixate the syringe holders to the moving head.
Attache everything.
Generate gcode
Without temperature settings
Very low extrusion speed
Open the gcode in a text editor and replace "E" with "E-"
[we want to pull the filament not push it, you can also change the firmware, but this was easier for me]
Print and use the live control panel in repg to tune the flow and speed.