Not sure if others have done this as it is a bit tricky to do and not
destroy the display- but the results are fabulous. Here's a pix of my HF-150
under medium lighting conditions:
http://www.parelectronics.com/pics/hf150bl.jpg
Lighting is supplied by a pair of hi intensity T 1 3/4 green leds. The
reflecting film and adhesive is carefully removed from the rear of the
backlight and is replaced by a machined acrylic specular plate that has had
U slots milled into either end for a press fit of the LEDs. Total current
drain is only 3.5mA. Many years back I had installed one of the lowe
backlight kits and was alwyas disappointed with the results.

Dale W4OP