Can you tell us, at what level this is going on at? Also I'm not quite sure what specifically you're looking for. Just having the right item creation feat and creating the needed phylactory is enough. So is CL 11. Demi Lich is more of a problem, you need to be level 21 have the right epic item creation feat, especially because its a LA +8 or your CR increases by 8 (cant remember).

Anyways... I would not suggest demi-lich. Your abilities go crazy poor other party members.