I put an idea like this into practice a couple of years ago. The first requirement is that the knife sheath is kydex so that a Spderco G-clip can be installed on the side of the sheath away from the body. The second requirement is that you cut off the bottom of your pocket. You then simply put the knife into your pocket with the G-clip attached to the edge of your pocket. The handle will of course be visible ,but even a reasonably long T-shirt will cover it.
In fact I cut off the bottom of both front pockets on an old pair of hiking pants and have carried knives as big as the CS Gurkha kukri in one pocket and the CS LTC kukri in the other, for many hours at a time. I find a pair of sturdy suspenders keeps my pants from sagging.
I find that it's very easy to quickly draw a knife in this position as the handle is below the waist, instead of above the waist, as with conventional belt carry. However, as someone said above, resheathing the knife takes a little longer but really, who cares.
I love this system as it quick and easy to drop the sheath and knife into your pocket at the beginning of a hike and equally easy to pull the sheath and knife back out when you're done.
You can pass dozens of people on the trail, who might be horrified at the sight of a big knife bouncing on your belt, who won't have a clue you're packing heavy metal.
I got my spouse to actually sew on a pocket extension to the cut-off bottoms of my pockets, so that I can actually use the pockets to carry small items as well.
This method may sound crazy but I find it works beautifully.