Getting the LiveUser examples working can be somewhat difficult for developers who are new to PHP and PEAR. Here is a list of steps necessary to get the example4 and GVN examples working with a MySQL database in LiveUser 0.16.12.
Install PHP and MySQL OR Sign up with a web host that provides PHP and MySQL.
Now install the PEAR packages LiveUser, MDB2, MDB2_Driver_mysql, HTML_Template_IT, HTML_QuickForm, and Var_Dump. Command line will be something like pear install --alldeps LiveUser-beta (repeat for each package). If you used the go-pear.php, there's some web-based way to install packages through that, but I haven't used it.
Now create your empty database in MySQL.
Now copy the files of example4 to your web root. On my Linux system the examples ended up in /usr/share/pear/docs/LiveUser/docs/examples and my Apache web root is at /var/www. You can find out where the examples are by executing pear list-files LiveUser.
Create the database by viewing the demodata.php through your web browser with a URL like http://www.example.com/LU/demodata.php?dsn=mysql://dbuser:pwd@localhost/databasename&file=/var/www/LU/demodata.xml&create=1. You must replace the file path values and the database user, password, host, and database name with values appropriate for your own system. If this gives you a "success" message and you have phpMyAdmin or something, you should be able to look at the database now and see tables with data in them.
Edit the conf.php file and enter your database information.
At this point you should be able to view the index.html page through a web browser and log in and use example4.
To get the GVN samples going, first create a "GVN" folder under your web root.
Go through the GVN tutorials, starting from the beginning because there are dependencies, and save all of the sample files.
In most of the files I found that the include to LiveUser/LiveUser.php had to be corrected to just be LiveUser.php.
Copy the file Auth_XML.xml from example4 into the GVN folder.
Copy your database information and the LiveUser configuration array from example4/conf.php into GVN's conf.php and conf_admin.php files.
In example4, the users that are in the database are deactivated for some reason... in the peoples table change the values in the isactive column to 1.
The above steps got me to the point where I have the working sample app and pages that demonstrate adding users, etc.