If your server's PHP installation supports auto_prepend_file and auto_append_file directives to be modified, using php.ini or .htaccess file (depending on your PHP installation), you can configure your server to automatically include needed Instant Update files at the beginning/end of every single PHP file on your web site, thus avoiding conversion of your PHP files.
If your server is installed as server module, and not as CGI module you could try to create blank text file, name it .htaccess and place it in your manage/ folder, and place following lines in it. If such file already exists, just append following code at the end of it:
php_value auto_prepend_file "/full/path/to/your/website/directory/manage/iu-auto-prepend.php" php_value auto_append_file "/full/path/to/your/website/directory/manage/iu-auto-append.php"
Otherwise, if PHP is installed as CGI module create blank text file, name it php.ini and place it in your manage/ folder, and place following lines in it. If such file already exists, just append following code at the end of it:
auto_prepend_file = "/full/path/to/your/website/directory/manage/iu-auto-prepend.php" auto_append_file = "/full/path/to/your/website/directory/manage/iu-auto-append.php"
You can get correct (full) path to needed files by navigating your browser to yourwebsite.com/manage/iu-auto-prepend.php
If you can not modify those directives, you can ask your webhost provider to do that for you. If they can't/won't do that, you'll have to convert your pages.