Earth Special Forces is a Half-Life 1 modification, not a Unreal Tournament 2004 modification. With other words, you cannot play this modification on UT 2004, nor any other games except Half-Life, Counter-Strike v1.6 (not from the CS: Condition Zero package) and Day of Defeat (not the source version). Please also remember that Earth Special Forces is not for Half-Life 2 nor It's source games.
Ohh i think i know what he is tlaking about. OK well there is a mod. for Unreal Tournament 2004 yet i don't remeber how to get it but it's not ESF. It's an rpg Dragoball Z game you go through all of the stages and stuff. I know of someone on the forums that always takls about there homwpage. Look for a guy named J-Dude on these forums. Ohh look at esf chat and then scroll down and there will be a topic on when do you think 1.3 is coming out he is the one you are looking for.
This one is graphically more up to date than ESF, since it has a more recent game engine. It uses cel shaded graphics too. Its not for multiplayer gameplay as of yet, maybe in later versions. Its mostly meant for single player. It uses voice actors to imitate the entire cast instead of using clips from episodes and such.
They've done a lot on it and already have all their voice actors for every thinkable role. You wouldn't believe how many participants there were (btw, I was chosen for the role of Babidi ^_^)
If you want full details tho, you should PM "Goku SSJ" (not sure, thats the correct spelling). He's the leader of the DBZHOOD mod, so he'll have all your details. He's a member on this forum too, so you can search for his username.
Well, don't want to get slammed for advertising (mods can be harsh) so I'll leave ya' there !