How can I set up a local SOCKS5 proxy whose only purpose is to chain to an authenticated SOCKS5 proxy -- on OS-X?

Question

For access to certain resources, I use an authenticated SOCKS5 proxy which runs on a remote server. For various reasons, I don't want to use that proxy system-wide, only with specific applications.

Most of the applications I need to use the authenticated SOCKS5 proxy support SOCKS5 with authentication; however, some only support SOCKS5 proxies without authentication.

What I think I want is an unauthenticated SOCKS5 proxy server running on localhost, whose only job is to forward requests to the already-existing authenticated SOCKS5 proxy. Before I go about hacking together a solution, it seemed wise to ask if anyone already knows of one.

I run OS-X Lion, so the solution has to run there (if it's available via Homebrew, so much the better).