A Lich doesn't have much in the shape of body parts, and you need to find the machine to do it. A word of warning - at your probable party level, it's dangerous around there. Take care, save often, and keep a backup position. If you want the full spoiler, Select the text between the highlights below.
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From memory, what you need to do is:
(1) on entry level, collect one set of ingredients and one jar for every scholar you intend to promote to lich, and make sure each candidate has both a set of ingredients and a jar.
(2) Then go to the upper floor, go to the lab, and click first on the cook pot, and then on the Bunsen burner. An item called a Potion of Defedation should appear in your inventory. Your candidate should then drink it, and if you press Z you should see that your scholar is now a Candidate for Lich.
(3) Lastly, make your way to the bottom floor, find the lich machine, press the button on the console on the gangway to activate it, enter the one surviving cubicle (below), and press the button. Hey presto - you got lich!
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