Haumea is located beyond Neptune. It is one-third the mass of Pluto. Most objects in the solar system have very strange shapes. Haumea is one of the strange ellipsoided shaped objects. Haumea would likely become a moon of Neptune or Uranus like most other dwarf planets in the solar system. Haumea has a strange shape but it is really large comparing to the other irregular bodys. Haumea is very dificult to terraform from our point of technology. This is why we will need to put Haumea in an elongated orbit around its planet. Neptune would be easier because Haumea is a plutoid.
Haumea's rotational speed is incredibly high - about 3-4 Earth hours. The first thing that should be done is to slow that down to about 20 hours at the very least. A much slower day would cause the dwarf planet to slowly change its shape to a geoidal sphere. A thick atmosphere full of greenhouse gases (even up to 5 atmospheric pressures) would be needed for the planet, but risking that it would evaporate and escape into space, paraterraforming is nearly inevitable. The next problem would be the surface - as it is the case with other objects past Mars' orbit, it's very likely made up of ices in a high percent, causing it to turn into an ocean world once heated. Artificial continents would be required, a possible solution would be bringing tiny rocky asteroids to the dwarf planet.