Simple answer, you can't. Complete answer, only if you jailbreak it.
For a device that is meant to be typed on using two hands (unlike smartphones), I don't see the benefit of swiftkey/swiping-based entry methods. That said, did you know that you can split the keyboard into two pieces which may be helpful in certain typing scenarios? Put two fingers on each side of the keyboard and drag outwards horizontally (like pulling something apart).