I spent a lot of time developing my sword bouncing technique and I have finally found one that works every time and also will get you on top of the building/skyscraper along with your friend. This technique is exclusive to this website (at least till someone steels it) so feel lucky to find it Hope you like it:

Ok, first you get into a corner and get your mate on top of you, walk towards the corners of the wall whist looking directly up. Next get you mate on your head to walk backwards into the corner of the wall so his back is in the corner, this is so that if you slip whilst sword bouncing, you wont assassinate your mate. Ok now your mate is on top of you and your both walking into the corner (your mate back first, your front) the guy underneath jabs A+B+X as fast as he can and the guy on top just jabs A as fast as he can, you should still both be walking into the corner of the building on your ways up.

If you are right handed
Ok the next thing is how you hold the controller, I find that my right thumb can jab a bit faster than my left, so what I do is hold the controller upside down, I pull forward on the joystick with my little finger so I am walking into the corner and at the same time I hit the X button with my right hand (this is a safety, as I can jab faster with my right, I will block instead of sword and therefore not hurt my mate) and I hit the B and A button with my left. Be careful not to though grenades as I often have the controller on my lap when I am doing this and hit the trigger button occasionally.

If you are left handed
It should work for you to hold the controller normally and not upside-down so consider yourself lucky, remember to stay walking into the corner whilst jabbing the buttons and it may also benefit you to hold forwards into the corner using you little figure.

I can easily get onto all the skyscrapers in headlong except one using this technique (one of the skyscrapers has no corners to do it in).

This is one way of sword bouncing out of 3 but is the hardest to learn so if you can achieve it then well done.

Another way to sword bounce is by using B+X this is affective in a corner but not nearly as affective as the one above. This type of sword bouncing is best to be done when there is no corner to do it on as the type sown above does not work if you are not in a corner. The good thing about this type of sword bouncing is that is can even be done in the middle of a field and still work well although it is much easier to do against a wall.

Using this technique you should not walk into the wall as this is to hard to stay in the same place, if your mate standing on you head can turn around then this is best so you don’t kill him. So all you do it walk up to a face of a wall and get your friend to jump on you, make sure your ridicule is exactly in the middle between his legs and don’t yell at your mate that it is too hard to jump on your head perfectly in the right place because it is really hard to do although from the bouncers perspective, it doesn’t seem it. Ok, now you are on top of the bouncer, the guy on top hammers the A button as fast as he can whilst the guy underneath hammers the B+X buttons. If the guy on top jumped on you perfectly then you should start going vertically up, however if he jumped on you head slightly to the side then it will completely screw up.

The third and finial way to sword bounce is to use the trigger and X this is done in the same way as B+X but not as well so it is hardly worth motioning.
Note: when doing the trigger and X technique, be sure that the ridicule to the sword in on the border between blue and red so it is blue but almost red and you will ascend just fine however, as soon as the ridicule turns red, the guy underneath will lunge and the sword bouncing will be over.