Here's what I found which I trust will be useful:
When yeast feeds on the carbohydrates in the flour, sugar and other ingredients in your dough, the by-product is carbon dioxide. When this carbon dioxide expands in the dough it forms air pockets in the dough and makes the bread rise. The longer and slower this process is, the more complex and sophisticated the taste and texture of the finished bread. The decreased air pressure in high altitudes means that there is less air pressure pushing back against these air pockets, so the bread rises higher and more rapidly than it should. Typically, the dough will rise way up, then collapse during the baking process since the structure of the bread cannot support the volume of dough. Decreasing the amount of yeast by 1/3 to 1/2 will certainly help. Use the best quality instant active yeast (not rapid rise), like Red Star or Saf/Instant. Also, allow the dough to have an additional long, slow rise before it is formed and baked. After the first knead and rise, punch down the dough, place in a large heavy duty zipper plastic bag and refrigerate from 2 - 24 hours. If you are using a bread machine, program for manual and remove the dough after the final cycle. Then the dough can be formed and given a final rise before baking. If you have a programmable machine you can place the dough back in the bread pan, program for "Final Rise" and then "Bake". Don't allow the dough to over-rise during this last proofing - remember that it will rise more during baking.