Well once Live nukes your Xbox, you have to boot EvolutionX from CD. But, once that works, for those who want to not use a CD, they have to do some renaming.
Most people who get a nuked XBox from Live are probably running a non-flashable modchip and have xboxdash.xbe as their EvolutionX and MS dash as msxboxdash.xbe.
Once you can FTP successfully in, rename your xboxdash.xbe as msxboxdash.xbe (this is your MS dash), and transfer over EvolutionX's xbe as xboxdash.xbe from your PC.
BTW, always keep your EvolutionX CD as a backup. It doesn't have to be always updated with the latest version, but just having EvolutionX on a CD is great because whenever you do get nuked, you can just repeat the above process. You still will have your evox.ini settings on your HD as you will never lose those unless you youself delete the file.