How to Rewrite this URL?

I have to rewrite this url: http://mydomain.com/index.php/site/pages/id/17

to: http://mydomain.com/resident/new

The technical part here is that the use will provide the last two parts of the URL i.e. resident/new while entering data from Admin section.

How can I do this?

I have tired editing .htaccess file but without any success :(

Any ideas as to how to achieve this?

TIA

Yogi Yang