How to add bots into the maps
To add bots into an existing map (generically speaking) I suppose it should be enough to place
"bspc.exe" (a file that comes with q3radiant, but if you want to download it alone you can find it
here) in the same folder of the .bsp file (you may need to copy the bsp outside the pk3 that contains it, usually placing it into a subfolder called "maps"), and then launch "bspc -bsp2aas mapname.bsp". This should create an .aas file. Remember that the game does not load maps not packaged into pk3s, unless you set \sv_pure 0.
I know about an "optimization" option of bspc (to be used as a second command after you created the aas file), "bspc -aasopt mapname.aas", but I don't know exactly
what it optimizes (file size? Bot behavior?).
IMPORTANT NOTE: I just beginned studying
Q3radiant, to make a Q3A map... then I will try to configure and then use
gtk radiant or
netradiant to make a map for OpenArena. I don't know if the bspc that comes with q3radiant works with maps created expressly for OpenArena!