I read somewhere, after buying stretcher similar to those in shysal's picture, that spraying with leather stretcher then wearing the boots or shoes with very thick socks works.
I have one bunion and often use a shoe stretcher for that shoe. This is the type I have, with added 'bumps' for the chosen spot(s). I have even been known to tape an AA battery to the stretcher at a tight spot. You would need an angled one for boots like the second picture. The results work for me (I leave for a day or two), but there could be a danger of splitting the leather if you overdo it! Good luck!
Do they work? I'm fed up. I have two pairs of good boots. In one pair the left boot hurts my foot and in the other pair the right boot hurts my right foot. Id wear the 'good' one of each except one pair is black and the other green. Would shoe stretchers help? It must just be small differences in the stitching or manufacture that causes the problems. If both were wider that would help. Any ideas?