In order to make mods for, well just any game you have to be able to code aswell. If you have some one else to do this here is a little guide.

Now i am going to asume that you are using Gmax a your standard 3d app. If you don't, then try the import/export functions in your programs, and find something that both apps support. The only thing you have to remeber is that many of the formats that you can import into gmax has it's vertices broken up, so you have to make a very small weld (fx. 0,001), so that it all comes together again.

A good idea is to import a w3d file, so that you can copy objects like the ones used for the fire effects, and the housecolor (the faction color) objects. To do this you (after what i know) need a plugin/scripts, if you can't find one that is made directly for gmax, then try searching for a plugin for 3ds max instead, i think there is one call coolfile w3d importer.

After importing, delete all the objects that you don't need, and copy the fire objects and so on by holding down shift and dragging the object to the position you would like.

To export go to the tools (the last button on the top menu on the box in the right hand). Here you will find one called w3d tools. Push on the button. In there is are some checkboxes which define whether the objects should be exported as geometry. Marque select all you're objects, and make shure that everything is set to be exported as geometry.

Before exporting there is one last thing you need to do. Link the fire effects, housecolors and so on to your'e objects using the link tool.

I hope that this helped you.