Yeah, underscore is ok (I just tried it
)
As for what to put in, the pit cam values in the image should get you in the ballpark.
For the TV cameras the best thing is to open up sandbox and see at what dlong/dlat you want each camera and where you want them to take over. Put those values in n4cam and then tinker with Elevation after watching it ingame. In my example I put Tv1 Cam1 outside turn one so it'll cover everything from it's takeover point (10 meters after sf line) AND also the distance after it's position until TV1 cam2 takes over (yellow arrow) and then the same for the following cams.
In the lower left of the pic I included what angles nr2k3 are using to give you a good starter value if you want to try some fixed tv cams
Random thoughts:
Remember to always make sure the take over distance has the - in front, otherwise it'll be a headache trying to figure out what's happening lol
Keep the cameras in chronological order (cam1 at 500 dlong, cam2 at 1000, cam3 at 1500 etc) and you'll avoid another headache trying to figure out what's happening.
Keep Angle of Vision something other than zero for any fixed cams, it'll look weird and you'll have no idea what's going on. (speaking of AoV, wider makes cars looks closer)
When n4cam says t: switch tv it's not kidding. After having added some text in the attached image I had caps lock on and suddenly it wouldn't switch between tv's anymore. Lowercase is the way.
It's a good idea to save a replay of you and/or the AI running a few laps, that way you wont have to start a new session every time you want to check your adjustments.
Things did work the same in cam-edit (except for the ability to create new spectator cams) but now that I tried to open it for the first time in years it doesn't want to open, says it's missing COMDLG32.OCX or one of it's dependencies.