I will try my best to write a cogent post, but please be kind in any critique as I keep sneezing on my keyboard, and am fighting to keep awake... (hey doctor, is it possible I caught your cold over the internet??)
I am fascinated by this topic, one that has obviously gotten a lot of play on Canna Sensei’s forum, but which, in my opinion, cannot be played out. The idea that one can ‘train down’ the involuntary reactions to life and death situations, or ‘train up’ in the sense of concentrating on techniques which will survive these reactions more or less intact is a compelling one. I think an argument can be made for both of these possibilities.
It is very clear that soldiers, for example, can be successfully trained to perform fairly complex tasks under extreme pressure, and ‘fear’ of death. I put fear in quotes because it is precisely this fear which is mitigated by the very specialized and sophisticated training modern soldiers undergo. In David Grossman’s book, "On Killing" (which I recommend highly and need to re-read shortly), he talks primarily about the need of the military to eliminate the ‘natural unwillingness’ of soldiers to kill another human being in order to have them be good soldiers. At the same time, I think that these same training methods instill a certain ‘desensitization’ to the fear of death into the soldiers (Grossman may state this overtly, hint at it, or not mention it at all - I do not recall - hence my need to re-read...). This is all to point out that it is possible to reduce the fear that someone will feel in a life and death situation via specialized training. Of course this does not address the question of how much training is necessary, nor what specific training will accomplish this task, to say nothing of the cost to the individual being so trained... but the last is a subject, perhaps, for a different thread (come to think of it, it was a topic on another thread - which died out quickly for lack of interest, alas...).
As to the other end of the equation, about how one can train to function effectively while in the grip of the "chemical cocktail" (we really need to develop some shorthand for that - "cc" perhaps?). I think this is intimately related to issue #1, above. Nevertheless, let us assume that the effects of the cc have been mitigated somewhat by successful ‘psychological’ training methods, but that some large degree of the physiological effects of the cc are still present. Canna Sensei points out (quoting or paraphrasing Siddle - who I think I should read...) "Complex motor skills are skills which involve hand -eye coordination , timing or tracking ... and have multiple technique components" - and these are the skills which desert us when under the effects of the cc. Nevertheless, I believe it is possible to ‘slip’ the effects of the cc somewhat. This might be accomplished by following Siddle’s ‘formula,’ i.e. don’t depend on hand eye coordination. A simple example to illustrate this is the ‘hiji uchi’ - the elbow strike found in Kanshiwa Kata. When I have asked students why we hit our hand with the elbow, the answers often include things like: "because your hand represents the target," or "it’s to get used to hitting something," or even "because it makes a cool noise" (I sincerely hoped that the last was tongue in cheek...). I explain to students that in fact (or at least in my opinion) the main reason for hitting one’s hand is that after doing this thousands and thousands of times, this movement becomes totally instinctive - that no matter what is happening, a Uechika will always be able to hit his left palm with his right elbow (or even vice-versa for those who diligently practice their kata both sides!), and, most importantly, whatever is being held in the palm or between the elbow and palm, will be hit. In other words, this is a technique that, practiced over and over, imprints itself and does not necessarily depend on hand eye coordination.
Anyway, posting this does in fact require hand eye coordination, and some complex cognition (despite some nasty rumors to the contrary...) - both of which have been fading rapidly, so I will sign off...