I found a little cable which can help us to make a special usb flash drive for the boot loader!
Here is the cable :
We could just dedicate a small usb flash drive (256mb) and install the boot loader on it!
Then we hide it inside the pc !
Even if your HDD die you'll keep your boot loader for ever!
No more problem !
A smaller one, without cables :
A better one! A Flash module! :