I would recommend commanding cavalry with Orc Heroes, and use either the General or an Orc Shaman for the infantry.
You might also consider the Orb of majesty, since it would give the genral a re-roll if he misses a command roll. Of course, you might also get more mileage out of the Crown of Command, since it allows the General's first order to succeed on an unmodified roll of 10 or less. This is great for pushing far-flung cavalry into a charge.
Use the Gerroff! spell to break up enemy brigades and push units back. It is a really annoying spell!
And here is the critical piece of advice: When facing any Daemon army, make sure that your troops face your own table edge. This will prevent your Orcs from seeing the insanity and losing their minds. If at all possible, send only one unit across the table at a time. And make sure your troops bring plenty of dental floss! Rememgber this is critical information, and I'm only looking out for the Orc's welfare on this...
