I personally don't use my
Twinhan card to drive the motor so I can't help you much there. I know when I did try, it was relatively easy to use Twhinhan provided software to USALS.
In your case with Nexus-S same should apply. Does Nexus-S provided software have ability do doit? If not you can always search around and see if there are any 3rd party plugins that do USALS for Nexus-S.