SM nations can be done through the system info --> create empire screen, then you can modify the details through edit race details screen.
Note that most of the planets in the sol system don't support life.
More details here: hxxp: aurorawiki. pentarch. org/index. php?title=Create_a_custom_race
Also you can use SpaceMaster --> Fast OB creation to create ships instantly.
Have fun
EDIT: My link's getting screwed up, maybe because of the few posts I have
sorry