If You are playing CS1.6/CZERO just take podbot mm from my signature and install it. They are doing exactly what You want at default settings. The forum (if You have any questions) is here: http://forums.bots-united.com/forumd...aysprune=&f=47
I agree, go with podbot. I keep the maxbot cvar at 6 and whenever one real player comes in, one bot leaves. That same thing occurs until there are 6 real players in the server, then there will be 0 bots.