Yep, basically exactly the same way. You can just make a copy of the gauss platform, modify its stats to whatever you want and save it as a different planetmodule file. In the file you'll also see references to the name and description that the infocards will show in-game (starts with IDS_ ). These are located in the english.str file in the Strings folder. You can search the string file for that line (it'll probably be IDS_PLANETMODULE_GAUSSDEFENSE_NAME or something similar) to see how it's done and add your own for your module, then just point it to use those strings.
You'll have to create a new researchsubject file also, you can probably use any military structure unlock one as a base (hangar, repair platform, etc). In there you can change the tier, costs, and location in the tree. For locations, the "first" starts at 0, so the top-left most research that can exist is block 0, pos [0,0].
Then you'd add that researchsubject as a research requirement to your planetmodule, and add both the planetmodule and the research subjects to the TEC's build list and tech list, respectively
Question: Do I need to use the convertdata.exe file to convert the txt files that I edit to a standard entity file, and if I do how do I do that. Thanks again.
You don't need to if you don't want to, it's supposed to speed up loading times a little bit if the game reads straight from binary. But either will work fine. I don't remember the exact syntax, but it's in the beginning tutorial pdf in the modpack
