I want to try some things with the cheats on (cheap I know), how do they work. Editing the autoexec doesn't seem to work using the old method.

Well for minimal hassle you can use console to toggle God Mode, See All Enemies, high levels and give yourself any weapons in the registry on that page.

http://au.ign.com/cheats/games/silent-storm-sentinels-pc-619907

Are you sure you've edited the right autoexec.cfg?
You need to edit the one inside \cfg subfolder using Wordpad or similar. Don't forget to make backup first.
Add a new line and type in this word without the quotes
"wirbelwind"

I'm having this same problem. I can't enter the line at the end. My computer keeps telling me I don't have permission to edit the file. Still trying to figure out why I don't have permission to edit files on my own system and who I apparently have to get permission from.

Your account may have been set as Regular User rather than Administrator. Two other things I can think of is whether the game is installed inside C:\Program Files and maybe User Access Control ?