Dude? What's wrong with you? I did not offend him in any way. ^^
And of course i do not know how he is doing this exactly, but the fact that he is editing this maps with UE2 gives him a lot of potential to create awesome things :-*
And since ur able to open those files you can get a clue on how he is doing this. I think its done by recreating entire texture and mesh files, then crypting them so the l2 client can read those files wo any error