Nevermind guys, I even tried checking videos on youtube on how to do it and I just can't make it work. I'll just have no reflections in my map that's it, it's too damn complicated just for making your env_cubemaps work...
its not that hard, even I can do it.
1. here´s how you can active your console in game: activate steam, go to your game list, right click on goldeneye 4.1, choose properties, click on "set launch options" and type -console and click "ok". this will show you your console when you`re starting the game. just let the console stay there. you can return to your console again in game by clicking esc.
2. for showing your cubemaps just try this out: create a simple brush and texture it with a reflective material, a marble texture for example. then put a cubemap next to it, as high as a player model. then compile your map with hdr enabled. when you´re in game, write buildcubemaps in command;. this should active your cubemaps. after that load your map again. and then you should see reflections on that brush.