I actually spent a lof of time flying and looking for brushes, buttons and different teleports.
Obviously we all know about the back teleporter from the hut's arch. But there is nothing more to it. First thing I notice was a totally unnecessary trigger brush on the back, the bad thing is that it was disabled at first, so I started searching for its inputs.
The inputs came from the disco room, so when I decompiled the map, I see there was 4 sets of buttons that actually enable that back trigger. But you only hace 10 seconds of spacing to complete the buttons. When I did it, nothing happened, but now the back trigger is active and I just got teleporter to a totally black room with computers. I finally did it, but there is one more problem.
I actually need to get into the disco room to do it in the first place, but I haven't see any info teleport, until I see a door on the floor, and it got me to the front hut where that ladder trap was, at first when I played the map I though the door is just fake but it's not, you can't open it but you can get teleported inside of it.
When I figure out that the room under ct spawn one of the walls was a button, and you have 30 seconds to active other 3 more buttons, and finally fall on a trigger teleport which is not active unless you activated the other 4 buttons before. So in conclusion everything starts at a glass wall that is actually a button, and you need to quick go to the two main river bridges press them, finally go to the main ramp rooftop the little one at its edge just another trigger that you're supposed to press? Maybe from the water?. So if you do that right you're supposed to fall into the little trigger marked by a decal.

It sounds very hard and it is, I wish zul read this, I spent 2 hours like a baby trying to understand, I'm not giving much detail to respect his work, maybe he want to keep it ultra secret at its triggers are named with zul.
I couldn't do it however, the first part into the disco room looks imposible, maybe it only works on multi-player, or I'm too slow, or something breaks, or there is another step I'm skipping. Who knows, only zul.