url rewrite help

["Matthew P. Smith" <m@xxxxxxxxxxxxxxxxxx>]

I need to rewrite requested urls from this:

domain.com/some-directory/

to

domain.com/some-directory/index.cfm

Can someone provide an example?  I need it to apply to all directory only requests.

I looked here, but did not see how to do it.

http://httpd.apache.org/docs/2.0/misc/rewriteguide.html

My apache knowledge is very limited.