It works, nothing goes wierd, and they appear in the game as brand new items.
Should work for any T file.. enjoy

First unpack the highest numbered dat file and get the 440001.xml, 440002.xml and the Tfile your interested in.
1) Go into the 440002.xml file and find a free text refrence number. About half way through the file there is a ruddy great list of numbers, just pick a free one.
note down the number, and then create a new line for it in order with the other numbers.(It'll make sense when you see it...)
2) choose something similar to what you want to create to use as a template ( a ship, station, weapon etc.)
2) Go into the 440001.xml file. Find the description for the item you want to use as a template and note its text 'refrence number'
Also set up a title and description in the same format as the other things in there for the new item you are creating. Use your new number that you chose in step 1 as the text refrence. Make sure you create it in numerical order and in the same format as the other stuff in there.
Names of Ship/stations end in 1, their descriptions end in 2, Names of wares end in 3, thier descriptions end in 4.
eg.
3551 'chocolate factory'
3552 'this factory makes chocolate'
3553 'chocolate'
3554 'a very nice fatty snack normally made into bars'
Have a look at the titles and descriptions of a few stations/wares/ships etc to see what needs doing.
3) Go into the relevent 'T' file and identify the line for the item you want to use a as a template by the using its text refrence number.
4) copy the entire line to create a new entry AT THE BOTTOM of the Tfile.
5) Go back to the top of the Tfile. Right at the top you will see two numbers, the second is the number of lines in the file. Increase this by however many new lines you are adding.
Make any changes to the new line that you need to (hint -> stormfronts mod kit ) and replace the textID with the new one you chose in step 1.
BTW, if you are setting up a factory/station the owining races name will be appended to the objects description. That way you can use one description for multiple factories (EG crystal fabs I believe have the same description and were done by egosoft like this)
6) Pack the whole lot up into correctly numbered/structured .dat , plonk it in your X2 program folder an hey presto, a new item in X2.