PODBot by Count Floyd (for Counter-Strike) HPB-Bot Template by botman (for Half-Life Deathmatch, Counter-Strike, Team Fortress Classic, and Opposing Force)
This package also includes the full source code in HLSDK 1.0 (the utilities code are removed because it's also available in current version of HLSDK).
Install the full version of POD-Bot 2.5 to your main HL directory. Then overwrite the original PODBot.dll with the included one and you should be able to play. Waypoints for the old maps are also required.