Lol, or just invoke them with a console (~) command where you state an alternate name.
I don't remember the parameters order but type /addbot without argument and you'll get them.
Could be : /addbot Sarge 5 blue 0 CacaBot
Sarge = bot model
5 = bot level(1-5, 5 being the hardest)
blue = team(red or blue)
0 = ? lol
CacaBot = bot name
if you are doing it with rcon, just remember to put /rcon addbot sarge 5 blue 0 CacaBot
as far as I know, there is no way to 'rename' a bot, just merely adding a new one with an alternate name