It might sound absurd, but I'd like to configure a bootloader on a USB flash drive to load from a removable HDD. The reason why is that the data fits on the HDD (where it has its own partition) but it has to coexist with other data and a previous partition, so I can't boot straight off the HDD - I tried setting the new partition as active (boot) and using bootsect but that didn't do the trick...
Any idea of how I could achieve the target? (tools, procedures...)
Edit: trying to boot windows 8 dev preview installer from a USB HDD with 2 NTFS partitions (the setup would be on the second partition) starting from a USB flash drive (1 partition, FS doesn't matter). The laptop has just one HDD, with two NTFS partitions.