Odd, I see a C++ example. Pasted from the wiki (and note that this is for Leadwerks 2):
TPick _Picked;
CameraPick( &_Picked, Camera ( framework camera here ), Vec3(GraphicsWidth() / 2, GraphicsHeight() / 2, 100), 0);
TMesh _Decal = CreateDecal(_Picked.surface, TFormPoint(Vec3(_Picked.X, _Picked.Y, _Picked.Z), NULL, _Picked.entity), 20.0/16.0, 32);
EntityParent(_Decal , _Picked.entity, 0);
PaintEntity(_Decal , LoadMaterial("abstract::bullethole.mat"));
AddMesh(_Decal , _Picked.entity);
My bigger concern was not finding an example for Leadwerks 3. Also, since you're not a developer I know you have restricted access to the forums but I'm pretty sure there were a few threads out there about it.