I'm getting the same error as ccrsport
When I "Set SSU Status" to true I get an error on the actual front end of my live site:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, [email protected] and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

Do you have any tips on how to configure SSU once it is installed?
my .htaccess is setup up as:
AddHandler application/x-httpd-php5 .php

#### BOF SSU
Options +FollowSymLinks
RewriteEngine On
# Change "/zencart/ to the correct setting
# if your site is located at root folder, then you should have RewriteBase /
# Go to your include/configure.php, this value should be the same with the value of DIR_WS_CATALOG
RewriteBase /zencart/

# Deny access from .htaccess
RewriteRule ^\.htaccess$ - [F]

RewriteCond %{SCRIPT_FILENAME} -f [OR]
RewriteCond %{SCRIPT_FILENAME} -d
RewriteRule .* - [L]

RewriteRule ^(.+) index.php/$1 [E=VAR1:$1,QSA,L]
#### EOF SSU
all except the first line, I copied from the installation instructs.

my shop config file is:
define('DIR_WS_CATALOG', '/');
define('DIR_WS_HTTPS_CATALOG', '/');
my store is located in the public_html folder of my website, which I believe is the root. Any ideas where the problem may be?