1. Jump on the box
2. Go with your crosshair over the corner of the box
3. Jump
_____
//hold all the time shift(slow walk)//
4. press w+s or a+d
Like this:
wswswswswswswswswsws or adadadadadadadadadadadad
5. If you "sink" in the box//here stop holding shift(slow walk)// run forward (first time you will stuck! thats normal!)
6. If you did that and don't stuck now
7. press w (or another key for example a, d or s) and shift(slow walk) at the same time!
8. Now you will fall in the box
That's all
If I helped you please give me a thanks
7.