I should note that the Wiki tutorials are very hard to follow, and outright not true (at least for me) in a few cases. A lot of that comes down to fiddly details which end up as utter showstoppers unless you find creative ways around them.
For one, hex-editing the exe is dirt simple... If you know what you're looking for. The Wiki tutorial says I should search for "XComGame\Config\DefaultGameCore.ini" which simply doesn't show up anywhere in the file. What I ended up searching for is "58 00 43 00 6F 00 6D 00 47 00 61 00 6D 00 65 00 5C 00 43 00 6F 00 6E 00 66 00 69 00 67 00 5C 00 44 00 65 00 66 00 61 00 75 00 6C 00 74 00 47 00 61 00 6D 00 65 00 43 00 6F 00 72 00 65 00 2E 00 69 00 6E 00 69" which in the file writes out to something like "X.C.o.m.G.a.m.e.\.C.o.n.f.i.g.\.D.e.f.a.u.l.t.G.a.m.e.C.o.r.e...i.n.i" That's what HxD shows it, anyway. In practice each of the letters is delimited by a hex 00 character which doesn't seem to map to a printable character but nevertheless prevents direct text searches. I found the above hex string by hand by finding XCOM, noting down its hex code, spacing that out with 00 characters, then searching for that until I found the DGC. This is what was tripping me up before, and it almost tripped me up again trying to apply this to a fresh install.
Secondly, the "Mods and Steam" article directs me to look for a log file which plain doesn't exist in my XCOM folder anywhere. A few log files exist in the broader Steam folder, but they're for stuff like QUBE and Viscera Cleanup Detail. None for XCOM, which means I don't know what to "block" in my host file. The "recent" discoveries (as of a couple of years ago) do give a static IP for EW, but I don't know how recent those are, and what to do when information contradicts. Blocking the game from updating itself and running in offline mode is easy to do. Messing with my Host file when I don't even know if I'm messing with the right IP is less so. I don't actually have an answer to that as of yet.
Apologies if it seems like I'm spamming the thread. I just found the tutorials rather difficult to use. Either things have changed since they were written, or my system is weird in some way.