- walk parallel to the base of the slope (don't sprint)
- assign any weapon (tryed with mp5 in backpack and with axe on back) to a keybind (let's say 3 - from the hotbar)
- once the animation to reach for weapon starts, turn torwards the slope and continue to hold W (walk)
- once you start walking fast up the slope, keep pressing (spamming) 3 (assigned key)