Well, I never heard of this before, but I always thought you can't add new Skills in their games. But, just for the heck of it, I had to see what happens when I try it.
I tried to do a New command and then I tried to Duplicate an existing one. Nothing happened that I could see. So, I went to close the GECK, but it asked me if I want to save my changes. Since that was all I opened the GECK to do, I didn't think I changed anything. I saved it and looked at it in FNVEdit. My two new Skills were there. So, I tried to open it in the GECK and see if anything showed up that way, but the GECK crashed. I could not get it to open that esp.
So, I fired up the game with that mod activated, to see what would happen, and nothing different happened. No crash, and my new skills weren't in the pip-boy.
I think the moral of the story is: Just don't do that!