How can the GENIUS that brought us 1337 Board: Element of War (the GREATEST and MOST INFLUENTIAL mod of our generation) ask such a silly question? Surely you are testing us, sire?
Are you trying to make a key that keeps jumping while you press it? In CPMA it'd be:
bind a +vstr one two
set one "-moveup;wait 2;+moveup"
set two "-moveup"
It's not perfect though as you can land during the wait 2 frame.
Yes, other than the mouse movement. I didn't say it was a good idea, just that this is how to do it. =) You reduce the strafe jumping acceleration while jump is held down in any case so this isn't useful for anything serious.
Scrub leagues or servers, you can't do anything especially useful with them. Engine I suppose though it would be trivial to change if someone wanted to do so. Jump reduces your vector I think because the engine treats it like another movement direction but it limits the vector size. So if you hold forward you have the standard vector. If you hold forward and strafe you do not get sqrt vector a squared + vector b squared as you'd expect, instead you just get the standard vector aimed at 45 degrees. When you press jump the vector will get aimed up at 45 degrees if you're holding forwards as well and then limited to the maximum vector value so only part of it points forward compared to the normal vector size.
Jump really affects your horizontal vector speed? I thought the two were independent.... Though I do notice something interesting with CPMA spec-mode -- odd "crouch-rub" (like wall rubbing, but I gain acceleration by holding crouch against the ground -- regardless of if I'm using strafe or not).