Hi. I hope this problem hasn't been solved, but I researched for quite some time and I found this solution for custom mod_rewrite rules.
I am currently using the rules below, but when I go to rewritten URL, it displays a 404 error.
<ifmodule mod_rewrite.c>
AddType application/x-httpd-php .xml
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /
RewriteRule ^folio/view/(.+)/?$ /?go=view&id=$1 [L]
RewriteRule ^folio/(.+)/?$ /?z=$1 [L]
</ifmodule>
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
I apologize if there is already a solution for this.