Get him to dash in to the computer terminal and stay on the other side of it and he will keep dasing and hitting the ground while you lay him full of nelcon and be sure to have a recovery capsule on hand (optional)or get your AP up and just fry him, then make sure to have a demeral on hand.
Another way to kill both forms of Dr. Lem
Use the following trick for an easy kill for both forms of Dr. Lem during the Boss fight at the end of Disc 1. Run around until your AP is maxed, and then enter the Boss room. When the battle begins, simply short on Dr. Lem and he will fall to the ground, dead like any regular enemy. After the FMV sequence, you will have to fight his second form. You should still be shorting. Just stand there and allow him get close to you. He will fall dead. When you save and start on Disc 2, your AP will have returned to normal. Note: This trick does not work on any other Boss.
Super short
Complete the game one time, and a replay option will appear. This will allow you start the game with an unnamed drug. The drug has the same effect as Apollinar, but when you short, it will allow you to run, decrease your HP slower, and will automatically kill all Bosses. When you use some Delemoter this status will go away, but every time you short after that it will still be a super short.