when the Installer launches...
it asks in what Volume you would like to install it, this detail you cannot miss, also you may customize it(install all less the support languages,etc) The OS does not install randomnly, you dictate where it is installed, you need to boot from the disk and then select what drive. once installed you go back to host computer and under the S.prefs>Start-up disk>select the External FW drive>restart, set-up accounts etc. Now the detail about the jumpers is just extra info, if your computer sees the drive then the jumpers are correct, the info was given out of my own experience with enclosures and loose drives, if you ever come across a drive that cannot be seen just look at the jumper configuartion. Remember you cannot fly through the initial installation without looking carefullt at what you initiate.