It isnt difficult, u just need to take a long running on the external part (i mean: 1 more step right and u fall).
But remember to have a al least 15 sensibility on mouse option, or u cant do it.
Now u just need to jump at the end just before the pipe, then u press left vs the wall. !!!RUN FAST!!!
Remember that u have to point the mouse on the left side pointed to the top !!!REMEMBER!!!
U dont need adv jump, but it dont help if u want to know it.
OK, now u know, try it sometimes, cuz u probably cant do it all times, u have 40% chances to get there, cuz u need to be very lucky or u have to know how to do it right!