It's hard to ask this question correctly I suppose. Basically, I want to be able to have a few mods that are level 4 OP, but other players to be able to still teleport and perhaps toggle the rain. Mostly though, to be able to teleport without easily being able to /gamemode themselves, if possible. It seems that it used to be possible (we used to be able to edit the exact buttons that would be available to the players- they would have magnet mode, toggle the rain, toggle the time of day and be able to teleport, but not be able to cheat).
The NEI config file (which is where I think it used to be available) is not at all the same, so I don't know how to do it now.
We are running FTB Infinity 1.7.10 if that helps any.
Best Answer
We figured it out. For anyone who also wants the ability to edit exactly what people are able to access through NEI, I will post a step-by-step answer here.
In the 'world' folder, there is a separate NEI folder. In here, there is a server.cfg file in which you can edit what you want people to have.
Step-by-step: IP Folder > World Folder > NEI Folder > server.cfg
What we did was OP everyone who plays on our server. So for what we wanted people to access, we put OP in the line, and for things we wanted only specific people to have, we put their name.
Here is a screenshot.