Hmm, normally I wouldn't talk in great detail about a particular technique. But we were talking about this technique over in Aikiweb and it was one of those techniques that done in the 'normal' way doesn't really seem practical whatsoever. However, I had previously asked Sensei about it and he mentioned that he too at one time was unconvinced of the viability of this technique.
Sensei related to us how he met with Kancho Inoue when he visited Malaysia a long time ago. He then asked Kancho how to perform this technique. Kancho asked him to hold his hand and then performed the technique. Without understanding how and without pain, sensei found himself flipped on the spot. Kancho did this 3 times and sensei still can't explain to me what he did until today.
Sensei does this technique differently now though. He uses more of tai no awase with the free hand. Thus kuzushi is happening at the core not at the hand. In fact it feels very much like you are falling over his hand thus there is no real application of force whatsoever on uke's elbow. To me mae otoshi seems pretty appropriate here.
I'll put up a video link here once I find it in my HDD somewhere.
To revisit the technique (I'm more familiar with Hijiate, but the other 2 was described to be similar techniques. In hindsight, I find mae otoshi to be more relevant to what is being practice in Aiki no Kenkyukai rather than Hijiate which eludes to hitting the elbow to effect the throw), hijiate is done when we have uke's left hand with our left hand and using our right hand to go underneath his armpit and then palm up taking kuzushi, take a right foot sliding step forward, rotate the palm down and projecting uke forward. Kuzushi is achieved by leading the left hand outwards, and locking out uke's elbow using the right arm.
Now this is where most applications will vary. I'm not an expert but what I've observed so far.
1. Typically aikikai way, in ai hanmi (say kosadori), you make an ayumi ashi movement and kaiten so now you are besides uke in a similar stance. Some nage will have grabbed uke's wrist by now, some will just lead it outwards. Next the other hand will go just above uke's elbow and stepping forwards with the back leg diagonally into uke's space, throwing with a rotating hand at the same time.
2. Some will not go beside uke, and instead moving obliquely in the direction of uke's omote proceed with the throw. (the hands are almost crossing and thus real pressure is applied on the elbows).
3. The way kancho showed me though was quite different to how sensei got thrown. He basically utilises enshin into uke's shoulder and projects the throw through uke's shoulder. Some would say, once you've applied enshin into the shoulder and uke's on his toes, you then drive him into the ground. This is quite similar to how you apply a yonkyo.
4. I've seen another method and typically this is used in shiai. Nage basically holds down onto uke's hand and brings him down with force. This is reminiscent of the unofficial 7th technique. Or a variation of nikkyo where uke's arm is straighten instead of bent. I don't know this is even accepted as a mae otoshi variant or a what, but for most it looks almost the same and I thought just to mention it anyway.
I'm sure there's many more intricate details that I've missed in this list. Its not meant to be exhaustive. All I'm doing is saying that the talks in Aikiweb raised my curiosity a bit since we seldom practice this technique. Thus I revisited it and yes, the issue of non-compliant ukes who resist by bending their elbows and posting with their legs do happen. So its not as fine and dandy as most videos of uke flying forward from such a throw are seen. I don't blame the technique however and most Aikido 'analysts' will come up with a great number of reasoning why such and such technique doesn't work. Inevitably it'll boil down to the fact that we are employing technique instead of applying Aikido principles. If you achieve control of uke's center it is unlikely that he can resist your technique. If you don't, no matter how forceful the technique is applied, uke can definitely resist or counter.
Easier said than done. And as I've mentioned the ideal form for me is to follow sensei's tai no awase and disrupt his core to effect the throw. I don't know how long it'll take for me to learn to this but in the end it'll be far more useful than were I to improve on my elbow attacking techniques.