Hey Melktert15,
thanks for the request. In general you could use the CoD4 GSM for older CoDs too. That's because all older CoDs are using the same rcon protocol.
The main problem with CoD1 (and also cracked cod2) is, that you can't exactly identify an admin by it's guid.
It could work, if we use an other identifier for players (ip or pid for example) but this would fuck up the whole GSM because we use the GUID for every player related action.
Can you send us the output of the "status" command on a cod1 server with some players and also a part of the games_mp.log? Then we can take a look and see if we maybe find a solution