I struggled to get my first model to dat format, mostly because I am an utter newb to scripting/programming/computer software tweaking. I've decided to write a quick abc for others with a similar lack of experience who want to join in but are anxious of wasting time.
I found the page http://oolite.aegidian.org/cyoship2
/ useful for modelling with Wings3d upto a point, but one or two things could be clearer for the newb.
A: Make your model. How to do that is out of my scope, but the above page is helpful here.
B: Select Whole Object (the fully shaded cube), select your model and check the number of surfaces and vertices. Try not to have too many of these, less than 200 of each, if possible. You can have more for a bigger ship. More complex ships tax your graphics card more and may slow down the game.
C: Follow the guide above until it says 'Save Your Work". Make sure your auv and model file have the same name (I got a fault on converting, when they were different).
D: Press the menu marked 'Window' and choose Outliner.
E: Choose the auv file you chose and right click and choose 'Make External' (It took me an hour to find this out by myself!). Save it as a .png.
F: Follow the guide until it says: 'Converting for Oolite'
G: Get a copy of Model Utilities, available in on this board and Python25 (if you don't already have it) from http://www.python.org/download/releases/2.5/
H: Download this to your main drive (C: for example)
I: Put the Obj2DatTex.py file from the Model Utility file into the Python25 main folder
I: Export your Model as a Wavefront (obj) to the Python25 folder. This will also make a .mtl file, which is your uv graphics.
J: Open up your 'DOS' box, by pressing Start on you PC, then choosing 'Run' and entering CMD.
I: In the Black Box, change your drive to Python25 thus:
J: Then type: Obj2DatTex.py <Your Model Save File Name>.obj (i.e Obj2DatTex.py Hornet.obj) and press enter.
This will then convert the file and you will have a dat file in the main Python25 folder.
I hope I didn't miss anything out.
I'd like to thank CptKey, who was a life saver and everyone else who got me to the finishing post.