Here's my modified .exe as well as the necessary .rfa files which allow you to play against 256 players/bots in coop mode:http://s000.tinyupload.com/?file_id=71794752926419748796
Extract 256BotsV2.7z using 7zip
, open the README file and follow the instructions.
For other Battlefield 1942 mod/s of your choice, you have to edit the game.rfa (Found in Mods/"modname"/Archives/bf1942 folder) using WinRFA, select AIdefault.con, find "aiSettings.setMaxNBots" and change 64 to 256.
Please let me know if it works.