The last - maximum units removed for BI set of files I tried didn't work for me as it was based on a mod and not vanilla - don't know if that is same one or not...

I did do some instructions on removing units here:
http://www.twcenter.net/wiki/Removing_Units

the positions for the custom battles are determined by co-ordinates in
custom_locations.txt in the data folder, you can add, delete or change battle postions.