I'm not an expert, but I study and practise my own bastardized, integrated system. I'll throw what I can out here, and if it's useful, good. If not, oh well.
I use to grip my well-used 16.5" khuk with my pinky below the handle ring, and the other fingers above, but staying on the wood. Lately, I've started to let my index finger and hand-web up on to the brass a little. Just enough to free the hand up some. It feels free; that's the only way I can think to describe it. Again: this works for me personally, so always do what works for you.
That grip, combined with the handling qualities on my particular mid-weight khuk allow me to take advantage of the balance, and control it to my advantage. An example: If I hold the khuk in my right hand, well gripped but my arm hanging freely at my right side, I can raise my arm at the elbow and sort of whip my arm out, the khuk and hand turning in the air, aimed at the target's left side (say, shoulder/neck junction), and with a slight push of my shoulder and downward wrist motion, the 'sweet spot' area impacts with great force. It's easier done than said.
I think that type of stroke was described in another forumite's post about his Bando class. I'd been using that stroke with tomahawks, and later my khuk, so maybe I'm on to something.
Here it is:
http://www.bladeforums.com/forums/showthread.php?t=400528
Anyway (and sorry for my long winded 'simple' explaination), onto my little technique.
My Stance: Khuk in right hand (if you're right handed) with the blade's spine almost pressed to your belt, held horizontally, left hand in a guard position, left leg forward, right leg rearward (incase you have to step back to dodge, you already have a footing, and you can step forward easily to close with the target...important with contact weapons, lol). It is a sort of twisted-feeling stance, but I'd rather think of it as 'springy', like a green hickory pole. Also, to anyone that tries this: Make the stance your own thing, and make it fluid. Words are inflexible, a body is pliable, and my vocabulary is only so big.
The khuk in this position looks like you're about to cut your target from left to right on the belly, but, it can do much more than that.
From this position, try a quick cut upward, stem to stern to chin along the breadline, then at the end of your swing turn the khuk around and crash the edge onto the target's head or shoulder or whatever with a good snap. It's very fast with practise.
You can also block or parry from the Stance position, with either the blade's edge or flat. Just experiment, I think the stance is a versatile starting point.
Now that I've got that out, I'll try to cover the specific points of Azsoldier's first post.
My best idea for a quick, quiet-ish sentry removal, would be either hard chop to the back of the neck, or a hard chop to the bare cranium with the edge or flat of the blade.
My attack on an advancing attacker would be to bring the khuk over to my left side like in the stance (because a stance would probably be a good way to die fast in this situation), and parry the attacker's weapon or weapon hand (say rifle-mounted bayonet, or hand-mounted knife; or at close range, knock the bastard's loaded rifle bore away from your body and press yourself up close so the target can't bring his weapon to bear, then maybe beat his head in with the khuk pommel), then follow up with appropriate action--kill stroke, whatever is needed. Also, if it would buy you a second by scaring/distracting/hurting your advancing target, throw the khuk at him and rush in with a smaller knife (like a Ka-Bar or Hissatsu; forgive me khuk-nuts...
).
My choice for disableing would be to strike low on the target's shin. I tend to crouch when in 'ready mode', so I guess this strike wouldn't be too difficult. Or if you have a 30" sirupati, lol. I might also choose a strike with the blade's flat to whatever extremity needs some whackin'.
And, I think I covered the low-angle attack just below the Stance area of my, article I guess.
Once again, sorry for the long wind. At least it isn't broken wind.
These are the things I've learned, and I've not tested any of this on anyone for legal and moral reasons, lol.
Take what is useful to you.
Also, I highly recomend testing strikes on tree trunks (dead ones, hitting live things is never nice). Sometimes my khuk 'bucks' on some hits, usually blade flat hits. Once I figured out what hits it doesn't like, no problem. I just think it would suck if a khuk 'bucked' at a critical "contact" moment.
Good luck, take care.
