Waste of a good drive when they all boot from CD drive anyway.
1st BIOS must be able to boot from USB
2nd You can only boot from an active partition and only one active partition allowed per drive (I think)
3rd Difficult to make a bootable Ex HDD via USB, a USB stick can be done with the HP format utility, not sure if same can be done with a partition.
You can remove the drive from its case - connect internally, partition and format, make first partition active and install boot files on there, then fit back in the case and see if it boots