openSUSE 12.2 booting from an external USB disk

I wanted to run OSS12.2 on a Windows 7 laptop without changing anything on the machine itself.
Normally I use a bootable USB stick with SystemRescueCD on it but I wanted to do some more OSS testing.

Here's the procedure I followed:
- Download OSS12.2 Gnome Live CD
- Start the installation wizard and choose "custom partitioning"
- do not change anything on disk /dev/sda because that will be your internal laptop disk
- create a boot partition (100mb and ext2) - in my case /dev/sdb1
- create a root partition (ext3 for best performance) and others as you normally would (swap, home,...)
- modify the GRUB2 configuration so that it is installed to the BOOT partition (deselect all the other options)
- complete the install.
- Important, before reboot make sure that the boot partition is correctly flagged as bootable. (use fdisk to do this)

Done.

P.S.
As always, everything worked straight out of the box, except for the wireless.

Manufacturer: Dell Inc.

Product Name: Inspiron 1545  

 I just had to run /usr/sbin/install_bcm43xx_firmware and reboot to make it work!

The GRUB2 graphical menu worked after running all the updates.