I used Frank's method on a '49 Gibson J-45 and it worked quite well. As always when using wood dust for fill you have to test first to make sure it will match - using dust from the wood you're filling usually does not match.
The gouge/divot method also works well but takes some practice. I've used this successfully on tops.
Here's a photo after I did the repair on the J-45. I couldn't find a before photo but the board was a mess, the guitar had been sitting outside in a shed in Alabama for years and was almost beyond repair. Anyway the divots in the board were in the usual cowboy chord places and since I had to refret it anyway I was able to sand some of it out. You can kind of see the divot locations in the photo with the reflected light.
