I've finally sorted out all the problems with running Silverstripe on kiwihosting.net.nz. I've posted the installation procedure on my own blog, but it makes most sense to post them here too. So here it is:

Installing Silverstripe on Kiwihosting.net.nz

Download the latest Silverstripe archive and decompress it to a directory. Open up sapphire/main.php, and search for the following line:

$baseURL = dirname(dirname(dirname(dirname($_SERVER['SCRIPT_NAME']))));

Replace this line with:

$baseURL = "/";

In version 2.2.2, this is at line 149. Upload the Silverstripe files to the server as per normal installation. Next, create a new .htaccess file containing the following:

php_flag zend.ze1_compatibility_mode Off
php_value allow_call_time_pass_reference on
php_value register_globals off

### SILVERSTRIPE START ###
RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_URI} !(\.gif)|(\.jpg)|(\.png)|(\.css)|(\.js)|(\.php)$
RewriteCond %{REQUEST_URI} ^(.*)$
RewriteCond %{REQUEST_URI} !(/awstats/*)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* /sapphire/main.php?url=%1&%{QUERY_STRING} [L]
### SILVERSTRIPE END ###

Upload this .htaccess file to the root directory of the server. Next, complete the standard installation procedure. The server may complain that mod-rewrite is not working; this is okay. At this point, you may need to upload the .htaccess file again, because the installer may change it.

Download the file mysite/_config.php (via FTP). Add the following line:

Director::setBaseURL('/');

Now upload mysite/_config.php back to the server. Silverstripe should now be installed, and work correctly.

Some hosts still have globals turned on????
They probably don't. I messed around with the files quite a bit, trying things that others suggested. The most important line in the .htaccess file is the first one. It will probably work without the other two lines below the first one, but I didn't experiment further, so I left them in.

Hans