I was wondering the same and did a little digging. Here is what I found:
1) The modification looks like the ones done by these folks here: http://www.sciencecenter.net/hutech/canon/
2) I think he means 5 frames at 1 minute each or 10 frames at 2 minutes each. These would then be stacked.
3) No dark frames to eliminated sensor hot spots. These are loaded in PS as a separate layer to exclude any "false stars".
