Hi,
I have some more information for you if you are still interested...
As I said above, you can't edit anything while in WinRAR and to extract everything then package it all back up again you compress it which won't work in the game.
But I did some more messing around as I still wanted to know how to mod this game and found out something interesting, to make it work you have to create a "non-compressed zip archive" for the game to read.
So here is what we do...
Go into where you installed Supreme Commander, then into the 'gamedata' folder, take a copy of the file 'units.scd' so you can mod it, I copied it over to a 2nd PC that has WinRAR installed into the Shared Documents. Next I moved to the 2nd PC and cut the 'units.scd' file, pasted it onto the desktop and opened with WinRAR, I then extracted everything which created a folder on my desktop called 'units'. Inside this folder was another folder called 'units', so I renamed that to 'units1' and cut it from there and paste it onto the desktop.
Next, I deleted the 'units' folder and renamed 'units1' folder to 'units' then went inside. Now I see a heap of folders, remembering from the units modding guide from this site, the folder names are relevent as follows:
UEA - UEF Air Units
UEB - UEF Building Units
UEL - UEF Land Units
UES - UEF Sea Units
UAA - Aoen Air Units
UAB - Aoen Building Units
UAL - Aoen Land Units
UAS - Aoen Sea Units
URA - Cybran Air Units
URB - Cybran Building Units
URL - Cybran Land Units
URS - Cybran Sea Units
(the others are not needed)
Ok, I wanted to mod the UEF Tech 3 Mass Fabricator, I thought that 25 Mass for 1500 Energy was crappy, find the folder called 'UEB1303'. Once found, open the 'UEB1303_unit.bp' file with Notepad, scroll down a little over halfway, you'll see Economy. Under this you'll see some information, look familur? They should..
Well, all I did was to add a 0 to the line:
ProductionPerSecondMass = 24,
So now it looks like this:
ProductionPerSecondMass = 240,
Right, save the file, close Notepad, close the folder window, now we must create a "non-compressed zip archive" for the game. Right-click on the 'units' folder, select the 'Add to archive...' option for WinRAR, it will open the 'Archive name and parameters' box. Under Archive format, select the ZIP option, under the Compression method, select Store.
Click Ok and let it do its thing, won't take long as no compression.
Once finished, you now have a 'units.zip' file, I copied this back across to my 1st PC into the Shared Documents, from there I cut 'units.zip' file and went back into the 'gamedata' folder. Now, the 'units.scd' file that's in there I renamed to 'units.scd.old' and finally I pasted the new 'units.scd' file there.
Ok, close the window, fired up Supreme Commander, started the Tutorial, rushed built up to Tech 3 so I could build the Mass Fabricator, hay presto, it worked...
Man, after all that I need a beer or 4...
Have fun...
By the way, if anyone from Cheat Happens sees this, if you want me to type this out a little better and submit it i'll do it tomorrow, going to have a beer...