Thanks to everyone who posted their suggestions on how to fix this. I ended up [mostly] following Mark's advice. I am VERY pleased with the results. I figured I'm not the first or the last to run into this problem, so I thought I'd post a step-by-step description of what I did for future reference.
First I ordered some AN426A-4-3 rivets from Aircraft Spruce. Actually, I ordered about 397 more rivets than I needed (hey, they won't sell me less than 1/8 of a pound!). Even so, this was my first time putting in a $2 order, and was pleasantly surprised they sent it to me via USPS and charged me only something like $2.50 for shipping.
With the rivets on hand, I took a piece of scrap aluminum, set it between two blocks of wood, and dropped my bucking bar on it (hey -- I had to do a practice run first, right?!).
I went through all the steps on the scrap piece, and since I liked the results, decided to try it on the wing...
So, this is what I started with....a right leading edge with a small but nasty ding/crack near the tip...
I got some 120 grit sandpaper and a small piece of 2x4, and made me a sanding block. I sanded off the tip of the ding, which made it a lot easier to drill it from the outside (drilling from the inside would have been a bit challenging because of the angle at which the drill would have to be in order to be perpendicular to the skin).
Then I put a hole in the middle of the crack. I started with a #40 drill and then final drilled to #30. This completely removed the crack.
After deburring the hole, I used a 'pop-rivet dimple die' to dimple the hole. I decided to dimple and not countersink for a couple of reasons. First, the hole completely got rid of the crack and *most* of the dent, and I would rather not remove more material than necessary. This is one of the reasons why I definitely agreed with Mark about practicing on a piece of scrap first.
With the dimpled hole, I put the rivet in, put some masking tape on it to hold it in place, and set it with the rivet gun. I set the air pressure on the gun to 20psi and only had to give it a few hits before the rivet was fully set. Now I REALLY know why they call these 'soft' rivets!
***Very important*** Do NOT drop bucking bar while fixing dropped bucking bar dent!!!!!
Finally, I used first a red and then a blue scotch-brite disc to make things look pretty.
So there you have it...
Mark, thanks again for the advice!