Here is a link to the RoDeO mod http://homepage.ntlworld.com/paul.macallister/RoDeO.zip
Very easy to use,read the "read me" and create your own battles with a few clicks of the mouse.
You can be juli gainst barbs and cart at the same time and much more and also adds Valour,Armour etc as u wish.
Then by clicking "trebia or historical map" and "apply to game data" it automatically applies changes to game files ,so when u boot up the demo ur choice of battle is loaded up and ready to go.
The author is currently working to include more maps besides the 2 in demo I think.
TotalWarCenter is down at the mo so I can`t include link to forum thread on this mod.