Similar to the colonization of Pluto it would require a few things.
Artificial Gravity
We don't want our settlers to be weak and have health problems because of Sedna's low severity, one solution would be to dig the plant into making it hollow and then increasing its rotation. Another model is to build bowl-shaped habitats and rotate them to the point of generating artificial gravity on their edges.
Sunlight
Sedna is a long way from the sun so erecting an alternative source of energy, such as nuclear fusion.
Communication
Communication would be very difficult (due to the time to receive signal) which required a great infrastructure, in addition psychological problems could happen due to the incommunication of the settlers with their friends and family for a long time.
Resources
Sedna has some resources being mainly water, methane and nitrogen with tolines.
Artist's conception of Sedna
