@joegilder - Thanks for your response, but the keyboard shortcuts menu does not show what the keyboard/mouse combo is to set the loop end marker. It does show that ALT + NumPad1 will set the start, and ALT + NumPad2 will set the end, but those are 100% keyboard shortcuts that do not involve a mouse click.
As I explained in my initial question, holding the COMMAND key while clicking the mouse will set the loop start point, but I cannot figure out what key to combine with a click to set the loop end point. There also doesn't appear to be a menu like the keyboard shortcuts menu for configuring keyboard/mouse shortcuts. It seems like there must be such a keyboard/mouse shortcut since the set loop start option exists... so I'm hoping I can figure out what it is since it's a bit more convenient then clicking a spot and then hitting the keyboard shortcut.
Please let me know if you have any ideas!