See the page Using a FlexBot Behavior for more details.
See the page Console Commands for more details.
Participating (As a Non-Host) In a FlexBot Game
No special software or downloads are required to participate as a client in a FlexBot game. Any user with the standard Half-Life client can connect to a FlexBot game and participate.
To join a FlexBot game, simply look for multiplayer games on the network or the internet just as you would any other Half-Life game. Get started by clicking the "Multiplayer" button from the main Half-Life screen. Find a game and click "Join" to enter the game. You may now participate along with bots and/or other players.