So I'm wondering if this is possible, or if its a hard-coded ability. I want to basically cause the player to perform a "sneak attack" (read: an attack that does damage based on what the player's current sneak attack multiplier is for their weapon, and does the whole "Sneak attack for XX damage!" message) during a normal attack with special circumstances. In otherwords, script or force a sneak attack to happen even if the player isn't performing a sneak attack and is detected.

If this isn't possible I'll probably just have to string together a semi-complicated array of perks/scripting to basically emulate a sneak attack using critical damage. Or maybe make the player 100% invisible and force him into sneak when the conditions are met, if thats possible (and if it is, any pointers on how to do it? is there a way to force the player to enter sneak mode and not leave till conditions are met?). But ideally, it'd be great if I could just go "Make this a sneak attack", because then that would be much simpler

Thanks for any help

Perhaps you could try another avenue of attack regarding this conundrum. You could try having the subject invulnerable or "ghost" to all attacks that aren't sneak attacks, when the player enters sneak mode nearby (or a specific sneak OnHit event) this property is stripped from them allowing the kill.
Ie: Not sneaking, impossible to kill. Sneaking, can kill.

Hmm wouldn't really make too much sense in active combat. Unless theres any other way, it looks like I'm going to just have to try and make several different conditions/perks for every possible sneak attack damage state and force the next hit to be a critical hit with that much sneak attack damage being done (which should be easy, since I can just set the critical hit multiplier to whatever the sneak multiplier is for that brief moment).

On that note though, whats the default critical hit damage without any multipliers on top of it?

Any help on this?

How will the player be achieving a sneak attack in the middle of active combat? Except for that level 100 perk.

Actually think I might have found a way of getting this to work. To my excitement I found out via papyrus I can force the player to enter sneak mode, then force sneak controls off, then make the sneak detection chance be 100% less (so you are always hidden) for the attack.

It isn't triggering right at the moment but I'm positive I'm heading in the right direction once I get it to trigger right.

The sneak attack is triggered when making an attack at the right situation with full stamina.

Just kidding, still doesn't work:

http://www.creationkit.com/StartSneaking_-_Actor

Anyone have luck getting this papyrus command working? It appears to not do anything despite saying it does - using it exactly like it is mentioned in the example produces no results.

I know, I'm kind of trying to fish in an empty barrel with the "official" skyrim modding community being basically dead on these here forums but on the off-chance someones actually using this command to good effect, would be swell to find out how you are using it

For those few brave souls who still go to this forum, I've figured it out

Apparently, for no real arbitrary reason, you can't enter sneak while performing an attack at the same time. Which means, "StartSneaking" doesn't work if you are in mid-attack, so you have to wait for the attack to finish before calling the function. I've edited the Wiki to reflect this information.