Information (datasheet) about stepper motor?
That looks to be an Epson stepper motor with the model EM-199, I have one that looks similar, and has the model EM-437, but mine is sitting unused because I cant find any documentation either.

UPDATE:
I just found something that may help you out. This is a comment from http://www.instructables.com/answers/How-can-I-use-a-stepper-motor-that-has-no-markings/

First you need to know how to wire it, for instruction on that go to http://www.piclist.com/techref/io/stepper/wires.htm 
To find the rated amperage you would need to take it apart then use a micrometer or Caliper to find the coil wire diameter (note: a ruler is not accurate enough) once you have the wire diameter change the measurement to inches in Decimal Value then multiply it by 100 then you have the amp rating. To find the voltage you need a ohm meter to find the ohm value then multiply ohms by the amps to find the volts rating. To find the rotation degrees then you need a controller to test this. 

Good luck!