Well the keys to bouncing are:
1) The run up
2) The strafe
3) The RPG if needed
4) The landing
1) For your run up you need to face about 45 or 90 degrees away from your target and usually a couple of steps from your sprint will be enough before you start to turn.
2) For an effective strafe try to mix a console with a PC so just turn and hold left or right in mid air basically and you will move further
3) If you need an RPG the best possible time to fire it is right as you hit the bounce. It gives you more boost than if you fire it at the top of your jump.
4) For a landing some bounces you need to crouch, like crash for example, but i got into the habbit of crouching for all my bounces and to me it seems like it helps
And you do not need to hold X when you hit a bounce, if you hit the 'sweet spot' it should fire you up so all you need to worry about is getting the right spot