Here's a picture of my bars, see the little black extension piece on the tip of my brake lever?
http://www.flickr.com/photos/xenologer/3754510488/
You want one of those.
Should let you grab onto the brake from either the 'flat' or 'bar end' hand position, if your brake lever is long enough to begin with...

As far as I know, these items are not manufactured anymore, but check ebay. search for 'brake extension lever' or somesuch. Mine are Delta brand, but there may be others...