The rules for Portal No OOB state "Any bind that is accessible from the menu" and a few others, but nothing about a bind for jumping to be on the up and down of the Mouse Wheel. Is it allowed, or is strictly forbidden? I just want some clarification.

Binding keys via the console is allowed as long as you don't include "wait" into the bind.
Binds such as 'bind mwheeldown +jump' are allowed as well as 'bind f1 "save quick;load quick"'

Okay, thank you for clearing that up for me!🙃