Does anyone know the .htaccess code to directly ban a domain from hotlinking images (but NOT blocking all domains)?

Try this

RewriteEngine on
RewriteCond %{HTTP_REFERER} ^http://www.hot-linking-site.com/ [NC]
RewriteRule \.(gif|jpe?g|png)$ - [F]

That didnt work, this is my current code:
Options +FollowSymLinks
ErrorDocument 404 /errors/404.gif
RewriteEngine On

RewriteCond %{HTTP_HOST} ^eagleimg\.com
RewriteRule ^(.*)$ http://www.eagleimg.com/$1 [R=permanent,L]
RewriteCond %{HTTP_REFERER} !^http://www\.eagleimg\.com/

RewriteCond %{HTTP_REFERER} ^http://www.gfxvoid.com/ [NC]
RewriteRule \.(gif|jpe?g|png)$ - [F]