How does this actually work? As I understand it, weapons such as the Cattle Prod and shotgun bean bag rounds cause enemies to become unconscious when their HP is drained, rather than killing them. Can anybody confirm this, or correct me?

You can usually tell they are knocked out because they lay there on the ground and their eyes blink a lot. Then pull out the 9MM and put a bullet between their eyes!

You are correct.

Include also Boxing Tape, Boxing Gloves and Golden Gloves.

Here are the wiki links to http://fallout.wikia.com/wiki/12_gauge_shotgun_shell_%28Fallout%3A_New_Vegas%29 and http://fallout.wikia.com/wiki/Cattle_prod_%28Fallout:_New_Vegas%29

Thanks. The bean bag rounds in particular will come in useful for a pacifist character.

Those weapons cause "fatigue damage" which knocks the target out. Fatigue is a left over from the Oblivion that wasn't used in Fallout 3. Obsidian used in in new vegas for certain weapons. Once there fatigue is reduced below 0 they fall unconscious. The physical damage they do is next to nothing,

Ah, that makes sense. How long does the effect last? I'm guessing an in-game hour.