You're describing what firearm shooters call "flinch" -- a conditioned reflex reaction to the recoil and blast of a handgun or rifle. The solution for cameras is the same: first, know what to expect, so you can school yourself not to react. Second, "dry fire practice" -- for guns, pulling the trigger without a round loaded, to train yourself to hold everything steady as the trigger breaks (the analogy to a camera is obvious). With guns, there's a third, "random dry fire" -- this requires a partner, who will hand you the gun, prepared out of your sight, with either a live round or empty chamber.
All of these types of practice revolve around detecting that you're moving (the camera, in this case), "flinching," at or immediately after the trigger break, due to anticipation of the recoil and blast, or the mirror slap of a large SLR, and random dry fire is specifically about aggressive detection and training out the flinch. To simulate this with a camera (doesn't even need film loaded in most), you'd do the same thing: use some method to cover the sound of advancing or cocking the body, and a partner hands over the camera either cocked or locked (with some cameras, there might be some faffing around -- for instance, SLRs without instant mirror return).
Of course, another training method for reducing or eliminating flinch is using a gun with much milder recoil and report -- say, a .22 in place of a .45. For the camera world, that would involve training with a TLR/bright-finder, RF, or scale focus camera in the same general form factor as the primary one you're trying to train for. Perhaps a box camera with a couple pounds of lead taped on? No mirror slap, a quiet shutter, but you could make a Shur-Shot Jr. or Box Brownie feel more or less like an RB67 (though you can't simulate the huge ground glass viewfinder). Perhaps a 2x3 Speed, Crown, or Century (built to be hand held, and worth having in its own right).
In the end, the only solution to a conditioned reflex with an undesired outcome is to retrain the relevant reflex. You can learn to hand hold at slower speeds, and much of it is simply believing that you can. I've hand held 35mm SLRs and viewfinder cameras down to 1/15 on many occasions, a 4x5 Speed Graphic (using the focal plane shutter!) down to 1/20, and many TLR and folders to 1/25 on many occasions. As noted above, I've also hand held (with a good strap) my RB67 down to 1/50, at least (don't recall if I've gone slower).