BotMixer is an optional add-on for MapMixer. BotMixer extends the standard UT2004 Custom Bot Roster, allowing you to create your own Bot Teams.
MapMixer is, by design, a mutator whereas BotMixer is simply an extension to MapMixer and cannot be used independently, as it requires the administrative functions of MapMixer.
As of MapMixer v2.30, BotMixer is included in the distribution archive and can be accessed by clicking on the BotMixer button in the Main page of the MapMixer Configuration.