So it's only for listen servers. That's what I meant, I'd just like to modify it anywhere but most Source games won't let you anyways.
Oh, I see what your saying, you can't use sv_cheats on a cheat free server. There is no way to change the default fov by the looks of it, there is actually command to do so, but everytime it defaults back to 90, can't find any way to keep it at 100 on startup.
What I have done is create a "fov.cfg" with the following lines...
sv_cheats 1
fov 100
And along with this create an "autoexec.cfg" with the following line...
bind "o" "exec fov"
I just press "o" at the start of the map, it does mean doing it everytime you start a new map though. I wish there was some other permanent way to shrink the crosshair, but this will have to do me I guess.