if you know how to make a bot, make a zombie bot with the soldat bot editor program, links are floating around somewhere, search function will help you out there. (they are like boogiemen who gurgle and eat brains) (you could also have different types of zombies *hint* idea *hint*)
next you are gonna want to mess with the features, decide if you want to deactivate certain features, how many grenades do you want them to have... all that junk.
you could do 1 of two things, you could remove your bots exept for the zombies and set the random bots number to whatever for bravo team then when you start the server ittle be set up for you
you could also use the command /addbot <insert name of bot here> and if you dont want to type it all over and over use the shortcut that is two slashes "//" and the last thing you typed is re entered.
thats all folks!