Marlin,
If its a SKP (Script) download, you just turn on your X3 Addon Manager and select Add, select the new Script, and hit OK.. Loads it right up. Just place the Script in a good known seperated location, like a folder called new script downloads, and load it from there. Then later you can delete it (with X3 Addon manager) if you need to.
If adding CAT/DAT files, you can add them into the main game folder of X3, renaming them next humber up, then in the mini boot screen, click on the 'load Mod' button and select it. You can only run one Mod at a time though, so if you have multiple mods, then only one shows at a time.
Bill
Bill there are 2 ways of doing the Cat/Dat files, you are kind of combining both here... If you add the cat/dat files to the main X3 folder as the next number in line that is the false patch method and there is no need to select them in the X3 Launcher, they are loaded as a patch with the game. That is what I do for a mod that I am going to use all of the time such as the Cockpits. If you want to test a mod and want to turn it on and off on demand you add the cat/dat files to the "Mods" folder inside the main X3 folder then it appears in the Launcher and if selected it is loaded if not selected it does not.
Marlin the quickest way to test that mod is the Mods folder (I find it easier for testing purposes than the script editor or plug in manager). Just follow these instructions;
1-Unzip the files to any location.
2-Locate your main X3 folder (c:\Program Files\Ergosoft\X3 Terran Conflict - or something close to that)
3-Look for a folder named "mods" if it does not exist create it.
4-Copy the cat and dat files you extracted into that folder.
5-Start X3 normally, at the Launcher screen (that is the first screen - see pics attached)
6-Select the "Select Mod Package" Button - note this button is greyed out if the mods folder does not exist or is empty.
7-Highlight the Mod you want to use and click OK.
8-You will be returned to the Launch screen and now click Start.
The selected Mod will remain active on future starts until you go back in and select the "Original" Button to turn it off.
This is what I have been doing to test, then if the Mod works and I like it I rename the 2 files to the next number and copy these numbered files to the main folder and make sure to turn off the mod in the Launcher.
You can do all of the above with the plug in manager, however I have been having some problems with it (perhaps it's Win 7) so I have been sticking to the manual method.
In the attached pics I have selected the AMS Mod as the example but whatever files are in your mods folder will appear.
The last shot shows the "Fake Patch" applied as patch # 11. The game should have Cat and Dat files numbered from 01.cat/01.dat to 10.cat/10.dat, so to add a fake patch just rename your 2 files to the next number in line and place them in the main folder as shown in the 3rd picture, that's it they load every time no messing with the Select Mods button and this allows you to add several mods plus have one for testing.
I started (and maybe posted) a quick version of this before, but I will clean it up and post it with the pics for everyone so it is handy.