The command-line installer seems to have very little documentation. This is referring to /includes/installer/CliInstaller.php and the install.php maintenance script. Please document it on MediaWiki.org, including what it is for, what the command-line options are, and how it's behavior may differ from the web installer (are there things you can do with one but not the other).
There is some built-in usage documentation printed on the command-line, now. However, it's in need of maintenance, badly needs full examples, and the optional vs. required parameter hints are incorrect. According to the usage docs, we should be able to call php maintenance/install.php ADMINNAME but that doesn't work, many more arguments are necessary.