It's not that hard. just use continuity to determine the pairs that feed the same coils. if you don't have a dmm, just short 2 of the wires together. if the stepper is harder to turn, they go to the same coil.
Once you have the pairs, it doesn't matter which one is A or /A (A Bar). If they are switched, the stepper will go the opposite driection. It doesn't matter which pair you call A or B. If you have them reversed, the stepper will go opposite direction.
So, hook them all up, get it running and then decide if the direction is correct or not. If not, switch a pair or invert the direction sense in sw.
Just a thought, are you sure its a stepper? that's a rather odd color (er, colour) scheme.
Finally, measure the resistance of each pair. With the driving voltage, use ohms law to determine current and make sure that your L293D will handle it. You are probably fine - printer steppers don't pull a lot of current but it's a good idea to be sure.