I think you are over simplifying things when it comes to being able to "incorporate" Austin into the passing game. If you look back at the games he excelled in his rookie year, you may have noticed that it came exclusively against MAN TO MAN coverage (Indy, Carolina, for example). Teams just don't play man against the Rams very often.
Say what you want about Schottenheimer, he was able to exploit man coverage when they ran up against it. Be it Austin, or even Givens, they are the most successful on crossing routes, when they can be matched up in single (man) coverage.
Teams force him to "settle in" to the windows of the zone, catching the ball while STOPPED. The only effective alternative to that is underneath crossing routes, or bubble screens. But Austin is just too small to run the deep dig, and sending him on "9" routes just isn't effective against 2-deep safeties. Again, he is just too small to win contested balls.
Forcing the ball to him, even with the Jet Sweeps, became very predictable, and less effective the more they tried.
IMO, for him to be effective, he has to rely on the others guys being more of a factor, (Quick, Britt, Cook) all becoming the focus in the intermediate passing game, which will open up the middle of the field for Austin. IF opposing LBs are forced to get deeper in their drop, it will give Austin more room on the underneath stuff.
Combine that with a successful running game, which makes the play action passing game go, it will now allow for Austin to run his routed BEHIND the LBs and in front of the Safeties.
But, with all due respect, running "pick plays" against zone defenses just don't work. I know I am in the minority here, but it just doesn't make sense to me to focus so much on making him the "go to guy" in this offense, when he is so easily taken out of the offense by simply playing zone defense against him.