It is called NDOT, Normal Direction of Travel. It is found in the super CV29.
More info on the basic NMRA CVs.
You will have to do some calculation, but since it is bit 0, you really just need to add 1 to whatever value is in there right now. Or use something like DecoderPro to handle all that.
Add 1 to whatever value is currently in CV29 to reverse motor direction.
I believe CV 29 is the one you need, and you must calculate the correct value:
http://jmri.sourceforge.net/xml/XSLT/pages/0NMRA.xml.html
I have a HO P2K GP7/9 that I want to run Long hood forward. I put a Digitrax decoder in it (DH165LO) The haedlights and direction do not agree. When in reverse the front haedlight is lit and whenin forward the rear light is lit. Can I use CV29 to change this loco to agree on light and direction?
Thanks Mike Dickinson