To my knowledge, Bush cannot circumvent a law made by congress unless he does it under war powers(which were not granted to him)or a act of Congress. I can see Congress putting a hold on only immigration from the evil empires but they do not have political cover to do more.
Immigration is a political hot potato. No matter what you do, someone is POd. The Mexicans have lodged a complaint with the American goverment for arresting those illegals in the Phoenix airport last week.(just a minor example) And they had falsified documentation!(surprise!)
This stuff takes time.
You underestimate the powers of presidency in a time of crisis. Why I don't know. What I said about shutting down immigration from terrorist nations is a relatively easy move for Bush. Tell me, if Bush did the right thing and stopped immigration from these nations do you honestly believe Congress would have fought Bush on this and be clamoring for more immigration from countries like Saudi Arabia? LOL.