Ok, I got it. It had to be /Users/johnmegan/~/Blockland/BlocklandLauncher.app/Contents/MacOS/BlocklandLauncher -profilePath
BUT if I wanted it in the LaCie Disk, would it be LaCie Disk/Blockland/BlocklandLauncher.app/Contents/MacOS/BlocklandLauncher -profilePath LaCie Disk/Blockland?