There was this video "accusing" linkje of doing it on spider crossings once... can't find it though. In theory it makes you turn 180º, fire a rocket at the ground, and turn 180º back again, propelling you forward... not sure if it's even possible.
In other words, it lets u fire rokits from uranus.
Edited by quake is potat at 11:14 CDT, 19 May 2013
They are allowed, in general they can be more work for nothing, they doesn't give that huge advantage....
The pros can do better rocketjumps without it, being able to variate more the inclination, the speed, the damage taken, etc.;
with those things you loose manuality;
but some pros still uses some scripts, in my opinion it's just a perfectionistical thing, a mental thing, just like having an ultra-complex and perfectly organized cfg.
Too long, didn't read: they are not particularly helpful, someone uses them mainly for the sake of it.