I'll keep this very brief and very basic because, quite frankly, it isn't hard or complicated so I don't see the point in making a guide more complicated than necessary.

Ok, first off open Editworld and make a new map, any size, it doesn't matter.

Now save the map, I find it easiest to save my maps in the MapSaves folder in the Warzone directory, it saves having to alter paths to different files, I'll explain that in a moment.

Now, you will need to place your custom tileset in the following folder: 

C:\Program Files\ pumpkin studios\ warzone 2100\ texpages (default install for WZ2100)

Next, go into the folder called mapDataSets, again in the Warzone folder. In here you will find a number of files:

 Ok, double click on WarzoneDataC1.eds and choose to open it in WordPad.

The third line down is the only thing you need to concern yourself with in this file: TILETEXTURES "TexPagesTertilesC1.pcx"

Obviously this is the directory where you just placed your new tileset, so all you need to do is change TertilesC1.pcx to whatever your new tileset is called, remembering to add the .pcx extension.

Now, choose File -> Save As, and save the file in the mapDataSets directory with a new name, and remember to add the .eds extension when you save to avoid it saving as a standard text file.

Now go to the mapSaves folder and open the map you just created, the file with the .lnd extension. Always open this in WordPad, as the formatting goes all over the place if you try and view it in NotePad.

 You'll notice the very first line dictates the DataSet to be used: DataSet WarzoneDataC1.eds This defaults to the mapDataSets directory, so all you need to do is change this to the same name you called your .eds file.

You'll also see slightly further down the page another reference to the tileset to be used. Again, change this to the name of your new tileset.

 Again, Save As, and add the .lnd extension.

A quick note: I'm currently using Windows 2000 advanced server, and Word Pad won't save in plain text format, so you may still need to use NotePad.

Now if you go back into EditWorld and open your new map, hey presto you'll have your new tileset available to use, now you need to install TMLink.

 I find it's best to right click and open with WinZip (or whatever archive program you use). Create a new folder, anywhere will do, and extract all files here.

Before going any further, just go to your WZ folder and remove the MakeWDG program, copy it somewhere safe otherwise it'll be overwritten when you install TMlink.

Now, double click the setup file in the new folder and you'll be taken to the tmlink installer. Just specify your WZ directory and hit the install icon. Simple as that.

Now, after you have completed working on your new map you will want to export it for multiplayer as usual. This will be slightly different now. It will come up with an options screen just prior to compiling the map, where you need to specify your new tileset as the one to use for the compile.

There is a text field for you to specify both a custom software and a custom hardware set of tiles, I don't normally bother creating a software tileset as pretty much everyone now has hardware graphics support, so I just fill in both of these options with the hardware tiles.

All you need to do is hit browse and locate your custom tileset (in the WarzoneTexpages directory) for both fields. You can also specify what feature set, fog type and weather effects before you compile.

 Make sure the checkbox for Use Custom Settings is checked, and hit the Start Export button.

Voila! Your new map with custom tileset is ready to be tested

Well, I hope this helps any of you who want to use custom tilesets on your way to doing so