Don't bother. You cannot truly affect Lanmola movement without scripts, and at that point, you may as well script one from scratch. Even with scripts, forcing Lanmolas (or Moldorms) to do anything is quite difficult, and it will usually not have quite the effect that you desire. It may be possible to force their direction to remain static unless they hit a screen edge, but at the same time, this may cause them to behave erratically in yet-another-manner.
'Lanmolas and Moldorms obey no natural laws.' - This was in my signature back in 2015.
I know that a few members here have replicated them in scripts and perhaps they would be willing to put them into the database; but you will only go mad trying to force internal boss enemies to do anything that they do not naturally do in the source code. Scripting them is not all that difficult, save that you need to plan ahead for wrapping around objects.
I may decide to have a look at a few of the bosses and allow editing some of their attributes for 2.60, but by that time, we may replace them with npc scripts that the user can easily modify from the editor. I am leery about changing enemy behaviour too much, primarily as it may cause old quests to break.
Be very careful with changing the movement type for boss enemies too, as this may cause undesirable side-effects. I seem to recall Lanmola or Moldorm type enemies leaving the screen if their movement type is set to something other than their default .This can be quite comical, but I expect that you do not want it to happen.
Edited by ZoriaRPG, 08 July 2017 - 05:52 PM.