Technically, a spellcaster forum post, but there are some crafting aspects.
Use an imbuer to make a suit for you specific for this type of at-home mana work.
minimum resists
Mana Regen 2 on all pieces
INT Bonus & Mana increase at maximum on all pieces
LMC 40% total and LRC 100%, for when you have to go buy raw materials.
Lich form has negative HP regen, but you don't die at 0 from simply being a lich (something still has to hit you to do damage to you for you to die).
However, it DOES have Mana regen bonuses.
The Shadow Wisp familiar from the necro Summon Wisp spell gives a surge of extra mana each time the pet flares, as it sits by you, based on your negative karma (which repeated casting of necro spells can get you fairly low, and a good rate from it). It also gives it to your party members, based on their karma as well.
Skill suggestions (can be a temporary template, using soulstones to move stuff around):
Necro: sufficient to cast lich form; try for 120, for necro book crafting
SS 120
100 Inscription
120 Meditation
120 Focus
120 Magery (for the best spell books)