Hi,
On the propwash board (from their site) the board has the 'Step' and 'Direction' pins are broken out to the edge connector. They appear to use the standard A B C D nomenclature. Each stepper will need two pins on the Arduino - totalling 8 pins in all as each stepper requires step and direction. - I am unsure as to why you say that the board you are using (the propwash) only requires one pin ?? - it doesn't, it requires 2pins per stepper.
But, no worries.
All built into AM. You ONLY need to assign the step and direction for AM - so 2 pins for each stepper. The actual stepper outputs (4 per stepper) are 100% handled by the VID6606 IC so that is nothing to do with AM and you don't have to do or assign anything to these. You just need to ensure your connectors are wired correctly. If they worked before, they will be fine here also. The output side - ie the stepper drive part is ALL controlled from the chip. Is is nothing for you to be concerned with - apart from, as I said above - ensuring the wiring between stepper and the propwash board driver is correctly orientated.
-----------------------------
Just for sh!ts and giggles - if anyone wants to use the VID6606 for their own project then there is a much cheaper option than the propwash or similar boards - especially if you are driving a lot of X27 steppers !. if your soldering skills are reasonable - and they only have to be reasonable.....
then you can just buy the ICs (the VID66-06) and a SOP 28 to DIP28 adapter (the DIP28 uses the standard pin header pitch of the arduino or standard veroboard, project boards etc. - 2.54mm)
You only need to add a single electrolytic capacitor of around 22uF for the steppers (calculated at around 5uF per stepper in use), and a couple of 0.01 uF ceramic caps to the IC VDD VSS
They are not even absolutely necessary but better if you want to go the whole hog.
Total cost per unit is around 2 or 3 dollars. Each unit supplies 4 X27 steppers.
Just a thought for some who may like to roll their own.
If you look at the datasheet for the IC, it is also clear that the pin outputs for the steppers (ie Stepper 1 A,B,C,D) are all together in a block so perfect for a pin header with no additional track routing, this applies to the other 3 outputs as well. It couldn't be easier as far as wiring goes.
Apologies for crappy image, my camera is being a bit of a begger today.....
Also, here is the datasheet for the VID6606 for the X27 type steppers.
Have fun.
Joe