5 wires unipolar stepper motor + L298?

Hi, i'm totally new to controlling stepper motors (i know how to do it with dcs), and i have a problem :

I have a unipolar stepper motor : http://www.seeedstudio.com/depot/high-quality-stepper-motor-12v-p-335.html?cPath=39_40 and this driver : http://www.seeedstudio.com/depot/datasheet/L298%20Dual%20H-Bridge%20Motor%20Driver%20datasheet.pdf

And i don't know how to wire it and to control it with my arduino, after seeing many things on the internet, i connected 4 wires to the "stepping motor" pins on the back of the driver and : EA to one arduino pin and EB to one other (but that's only 2, and some people did it with only two on others drivers and others with 4.... so i am really confused and i don't know what is the right way to wire it), Vms is connected to a 12V external source, GND to arduino grnd and +5V to arduino's +5V...

My code is the one mentioned on this page : http://arduino.cc/en/Tutorial/MotorKnob without the potentiometer thing, but nothing is working and since i'm not even sure about the connections...

If someone could give me tips, tell me how to do or point some stuff i did wrong, i would appreciate.

Thanks :)

Normally a 5-wire would be unipolar drive only, since the two windings are joined together.

With a little care you can drive such a motor bipolar, but you have to ensure that the common wire isn't carrying current between the windings - you can either drive both windings simultaneously at all times (so the common wire is at V/2), or turn off one winding completely (all 4 switches off) rather than any other "off" setting - that way the off winding is floating.

You'll still get transient currents between the windings which may cause an issue - thus the general rule that 5-wire motors are unipolar only (4-wire motors bipolar only and 6- and 8-wire motors are either).

So, i can drive it with 4 wires, not using the middle one for current, but for this i need 4 intputs from the L298 for the arduino ? My problem is that on the datasheet is mentioned i can control a stepper motor with some of the pins (EA, EB , I1 I2, I3 and I4) but which one shall i use?

You need to drive them so as not to cause current between the windings, which means knowing what you are doing to each winding for each phase of stepping - suggests you need to control all of them (enables can just go to 5V anyway of course).

PWM is not going to possible to microstepping is right out.

Normally a 5-wire motor would be driven unipolar though, hence the caveat.