Rewrite Rule

I have an application that is installed as http://domain.com/folder/ and serves pages as http://domain.com/folder/index.ext/parent/child/ and I'm trying to remove index.ext from the URL so that http://domain.com/folder/parent/child/ would work as well.

Does anyone have an idea on what rewrite rule I would need? I tried:

RewriteRule ^(.*)$ index.cfm%{REQU EST_URI} [QSA,L]

but that sends it to /folder/index.ext/folder/parent/child/ instead...

Thanks!
Andrew