AppleScript for Dropbox on External HD
I use to have multiple dropbox instances running at once. I think you can put db  app on the drive and use the same trick I did.

HOME=/Volumes/Whereever/you/wanna/go; /Volumes/Whereever/Dropbox.app/Contents/MacOS/Dropbox &amp;


One thing. With this method you change your default $HOME into your new path. So Dropbox will create a folder called Dropbox in that path.