CDM_ is currently working on a lichcraft plugin. The features he already added are the following:

• The energy system--a Unified Health/Magicka system; your Spells come out of your (fortified) Health, but you have infinite Magicka. Spell 'cost' is reduced by 90% in this regard, and can not actually kill you if you use too much. You can still die if someone hits you, though.
• Energy System 2 -- Energy drains continually over time, based on how many in-game hours have passed; you lose so much energy an hour, and a full 'Energy Meter' should last 96 in-game hours if you literally just stand around and wait for the time to pass. I've not tested, but assuming it works like with Skyrim (which it should, since the Script is like 90% the same as my Vampire mod), Potions and Healing Spells don't work (you can't really Heal a corpse, anyway ). You regain energy by siphoning it from corpses/other people (maybe Spells, if I can later -- we'll see)
• Detect Life - It's called "Soul Sense" -- Toggle power, long-range.
• Night Vision - it's called "Dark Sight" -- Toggle power, infinite duration
• A Feeding Spell - It's called "Soul Siphon" -- EXTREMLY rough right now, but let's you feed on energy from the recently dead. Eventually, I'll hopefully add "Anyone below 25% health + Instant Kill" to that.
• Core Bonuses: Resist Poison, Disease and Paralysis - 100; Resist Shock and Frost - 100; Water Walking (because in Oblivion Lich's float); Water breathing (since you're a corpse); Weakness to Fire - 100 for now, and I'm going to add a 'variable' bit, too, so it will get worse the weaker you are; resist Normal Weapons - 25.
  
  
  
  
  There are currently a few issues:
  
  

  - No Skeleton, so when you're an unclothed lich, you look like Imperial Armour

  - Helmet does not align right, no idea why :/

  
  
  
  
  If you got any ideas, suggestion, feel free to add them