If you are running the Virtual Appliance in a secure environment, you can enable it by editing the "installdir/apps/phpmyadmin/conf/phpmyadmin.conf" file and replace "Allow from 127.0.0.1" with "Allow from all":
Alias /phpmyadmin "/installdir/apps/phpmyadmin/htdocs"
Allow from all
ErrorDocument 403 "For security reasons, this URL is only accesible using localhost (127.0.0.1) as the hostname"
Then you should restart Apache to load the changes:
$ cd installdir
$ ./ctlscript.sh restart apache
Then you can access at the same URL with "/phpmyadmin" or "/phppgadmin", for example http://YOUR_IP/phpmyadmin>