Engine direction

Yes you could but it would be easier to create an MU (Lashup) and set them to run in opposite directions. You would use 2 different engine #s.

Ron

Ron has the right solution, and I think you'll find it a more satisfactory solution.  The directional lights, and electrocouplers usually work in a logical manner for the MU as well.  If you just connect two engines running together, you will get odd behavior from the lights and electrocouplers.  In addition, the crewtalk, whistles, etc. will be always active on both units.

For DCS, I think it would most likely confuse the TIU no end to have two locomotives running like that, but I've never tried it, and I don't intend to.