I have a question too.

I want add a fireball to my mod(as a throwing waepon), but I have no idea, who I can script, that (for example) the flying stone burns. So it looks like a fireball.

That's my itemcode at the moment:
["fireball123", "Fireball", [("throwing_stone",0)], itp_type_thrown|itp_merchandise|itp_primary|itp_crush_through|itp_can_knock_down, itcf_throw_stone, 1, weight(4)|difficulty(0)|spd_rtng(97)|shoot_speed(30)|thrust_damage(11,blunt)|max_ammo(18)|weapon_length(8), imodbits_thrown, [(ti_on_init_item,[(set_position_delta,0,0,0),(particle_system_add_new,"psys_torch_fire"),(particle_system_add_new,"psys_torch_smoke"),(set_current_color,150,130,70),(add_point_light,10,30),])] ],
When I hold the stone in my hand, it burns, but when I throw it, it doesn't burn. How can I add that it burns if it is flying?
And how can I change a new kind of damage? Like firedamage which isn't reduce by armor.