Redirecting in Mongrel

Rails
1

I’m setting up a website with Mongrel. One of the requirements is for
URLs to be redirected to different files than they usually would,
e.g.:

http://example.com/users/show/123-king-kong

Would actually look for the cached file:

public/users/show/123.html

And not:

public/users/show/123-king-kong.html

as it normally would.

How would I set up such redirection with Mongrel?

Thanks in advance,
Maurice B. Gladwell