I've read the bug fixes that address the issue of modifying the _config.php file and the .htaccess file, but installation still leaves me stuck on the "loading page".
I should say it leaves me on the loading page when viewed in FireFox,
it simply resets the login form in IE....?

I'm stumped since I've tried every possible thing I can think of to fix it.

<<.htaccess>>

### SILVERSTRIPE START ###
RewriteEngine On

RewriteRule \.js$ - [L]
RewriteRule \.css$ - [L]
RewriteRule \.png$ - [L]
RewriteRule \.jpg$ - [L]
RewriteRule \.gif$ - [L]
RewriteRule \.php$ - [L]

RewriteCond %{REQUEST_URI} ^(.*)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* /home/build33/public_html/highexodus/sapphire/main.php?url=%1&%{QUERY_STRING} [L]
### SILVERSTRIPE END ###

<<_config.php>>

<?

global $project;
$project = 'mysite';
Security::setDefaultAdmin('admin','password');

global $databaseConfig;
$databaseConfig = array(
"type" => "MySQLDatabase",
"server" => "localhost",
"username" => "build33_xxxxxxxx",
"password" => "xxxxxxxx",
"database" => "build33_xxxxxx",
);

?>

Are you accessing SS by http://server/~build33/ ?
I have also problem installing SS into my home directory /home/xmedeko and access it by http://server/~xmedeko. I was not trying to fix it, though.

try to change last few lines in .htaccess from:

RewriteCond %{REQUEST_URI} ^(.*)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* /home/build33/public_html/highexodus/sapphire/main.php?url=%1&%{QUERY_STRING} [L]

to:

RewriteBase /~build33/highexodus
RewriteCond %{REQUEST_FILENAME} !-f^
RewriteRule (.*) sapphire/main.php?url=$1 [L,QSA]

Note the %1 has changed to $1