We are unsure how microsoft will counter modded xbox with Xbox live. But here is the best we can do to fool it.
1a. Lock your big hard drive using the hdlock software so that you can have the original bios boot from your replaced HDD
1b. Or you can always swap between your orginal hdd and evox hdd whenever you want to play live.
2. Install an external switch that allows you to switch between original bios and evox bios. Can be done on any modchips or flashed xbox.
3. Use the ydash evox bios instead of regular one. That way, when you live installs, it wont overwrite your evox dashboard.
Of course, all this is "IF" microsoft implement security that way.
If I was them, I would not try to counter modded xbox but force people to buy the games. To play on xbox live, you still need to pay them a yearly fee(monthly next year maybe). Best way to counter piracy so far is the use of cd keys. So you first need an account, then you need to enter a cd key for each game you buy. That way they truly counter piracy....forget about key generators...if they detect a counterfeited key , they can always ban your Live account...I do think this is the way to go. And frankly, I don't mind buying games that I would play online just like I do on the PC.