Booting grub from usb

[Goh Lip]

I have a few OS I boot using usb drives. Each time there is a grub
update, especially with kernel changes, I will need to go into grub.cfg
to change all instances of say, "set root='(hd3,1)'" to "set
root='(hd0,1)'".

I've created a custom entry at 08_mefirst where this will not be
changed, but I still need to go to grub.d/00_header to effect the
changes. 

Is there any way for grub to recognize that the grub resides in
a usb device and automatically set to (hd0,1)? Or at least delete all
"set root='(hdx,1)'"

ps: I know it will still boot with wrong (hdx,1) with the correct
"search --no-floppy --fs-uuid --set c25a3c07xxxx", but it would be
better if all things are in place.

Thanks, regards - Goh Lip


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