It's easier to train for the physical rather than the mental aspects of the adrenaline rush, but any training is a simulacrum, not the real thing.
One way to simulate the tunnel vision, loss of fine motor control, etc. is to run to near exhaustion at your *maximum* capacity (anaerobic) before sparring. You should be panting like a racehorse, have spots in front of your eyes, legs shaky, and possibly feel nauseated. It's only really practical to do this outdoors and it's rather unpleasant (only the most dedicated will do it full-out), but it does come close - and it'll get you in great shape if you don't die of an aneurysm first

To really emphasize the fine motor aspects do some heavy resistance work that exhausts your arm/chest muscles before the sprint, say as many push-ups as you can (I suggest stressing the arms since that's where you'll notice the loss of fine control most). Remember it doesn't matter if you 'lose' in such sparring - you're objective is different (to master your body and emotions, learn what techniques are too fancy, etc.)
The mental aspect comes mostly from sparring, the harder the better (hard in the sense it presses you to your limits and beyond, not that you get the shit kicked out of you) and visualization/mental rehearsal. If you want to really stress yourself, simulate an injury such as being unable to use one arm (tie your wrist to your belt, say).
If you want to feel some of the emotional stress, arrange to have someone slap your face when you don't expect it. Try to 'capture' the feeling of the instant visceral anger this arouses before it dissipates (and don't kill the slapper). Tony Blauer has some good exercises for the type of verbal abuse that may precede fights.
Another separate route is to fear-stress yourself - perhaps by bungee jumping, rock climbing, etc. Concentrate on the emotional aspects (I don't want to catch you enjoying yourself
Regards,