> Is it possible to redirect using .htaccess from a folder that doesn't exist on the server?
Yes, your problem is very easy to solve using .htaccess. Here's a good place to start: Introduction to mod_rewrite [webmasterworld.com]
You can put the redirect into the top-level directory of the site (web root), and it will redirect the requests for the missing subdirectory. You can use either mod_alias or mod_rewrite to accomplish this. mod_alias is simpler, mod_rewrite more complex and powerful.