I thought about editing his files so that he did not try to run away after the first time you go to town, but that would make it so he would never run away ever. That would remove the storyline of saving him from Burne's tower and everything else.
I so seldom play evil so I'm not up to date. I've never seen the Burne's tower thing and have no clue how he gets there. He either runs off or you get ambushed in the broken tower. That's all I've ever seen. I did get him to stay and made Smigmal Redhand recruitabe. I avoided the tower fight with a dlg edit of the leaders file. Worked good for awhile, but not much use for your mod. Where did this Burne's tower rescue thing come from?
Well, gotta admit I don't play evil and never managed to get this going (though it certainly works) but it was added by Liv long long ago.
Steps for Burnes Tower are as follows: 1) Get Lareth in party in MoatHouse 2) Take him to Hommlet, he tries to runaway, let him. 3) Go to the temple of evil, find the backdoor, walk in. The guards will accuse you of killing Lareth. If you have high enough bluff/diplomacy/intimidate you can convince them that Lareth is alive and you will find him and bring him back. 4) Go to Hommlet, and Burne or the badgers will tell you that they captured Lareth. 5) Become invisible and sneak to the bottom floor of Burnes tower. 6) You find Lareth in a trance, you can use a dispel magic spell to free him. 7) Then you need to either teleport out of the tower, or make Lareth invisible and leave the tower. 8) Take Lareth back to his tower outside the ToEE and he will become a merchant and that tower becomes a safe haven you can rest in.