I used the splinter cell exploit, and personally i think it was RIDICULOUSLY easy
. No, it will not overwrite ANYTHING except your C drive. what you should do, is as soon as you load up the linux profile in the menu of your copy of SC, a new menu should pop up. now you have FTP. ftp all your xbox files (raw) onto your computer as backup, or you can use a program to make an 'image' of your harddrive, which you can restore later. After that, (you dont have to back up if you think you dont need to or if you dont have space on your pc) in that new menu, first press Backup M$. this will backup your M$ dash to your E:/ partition. Then press install softmod. Obviously, this will mod your box. Then press install
EITHER UnleashX or Evox. then it will ask if you want to do it on C or E. press C. If you already did one of them, dont do the other, it will just pointlessly overwrite. Personally, i like UnleashX A LOT better then Evox. if you dont want either of them, you can use the FTP capabilities and ftp your dled dash to the c drive.
Enjoy!