Adding boiling oil ?

Ok, as surprising as it is, it seems that nobody asked this question (anyway, did'nt found anything with the search, so...).

I would like to add boiling oil in the MTW2 Grand Campaign. I know that there are mods which add it, but they usually come with other modifications, and I strictly want JUST the boiling oil, if possible by modding it myself.

Sooo... how can I do ? :x
I do have Kingdoms, but I don't know how to make the boiling oil usable in MTW2 campaign. Could someone enlighten me ?

Additionnally, I'd like to know where I can alter the power/fire frequency of the wall towers. I'd like to make them a little bit stronger.

I was damn certain that I had already answered this, but... try the Retrofit mod. Grand Campaign with Kingdoms' engine's features.

If you want JUST the boiling oil and no other Kingdoms extras you will need—at a minimum—descr_walls.txt and descr_boiling_oil.txt. You may need additional files for localisation and the like. Note that there seems to some changes between M2TW and Kingdoms which could necessitate modifying more files to fix compatibility issues. It's probably not worth the effort—try the Retrofit mod first and see if you can save yourself the time.

Incidentally, modifying the towers will also require changing descr_walls.txt.