I've been looking around and I haven't been able to find anything for my specific problem. I'm trying to install BT3 on a 1GB thumb drive with OS X 10.5. I've followed the usb guides that I can find(like the basic on for BT2 on the Remote Exploit Wiki), and basically I have the BT3 and the boot folders on it, but when I run bootinst.sh, it does this:

sudo ./bootinst.sh
egrep: /proc/mounts: No such file or directory
egrep: /proc/mounts: No such file or directory
egrep: /proc/mounts: No such file or directory
Can't find device to install to.
Make sure you run this script from a mounted device.

any advice? (The flash drive shows up mounted on the desktop)
And also, is there anything special I need to do once I have Backtrack bootable on this thumb drive other than hold the option key when I'm booting to use Backtrack?

Thanks