1) Make your stage 1136x640.
2) Include this code:
stage.scaleMode = StageScaleMode.NO_SCALE;
stage.align = StageAlign.TOP_LEFT;
3) Include code that reads orientation (other forum threads discuss this).
4) Build a Portait and Landscape layout for each screen, and go to that layout per step 3, above.
5) Include the proper launch screen images (search Adobe's help docs)
Oh, and by the way, you must have AIR 3.7 installed and configured in Flash. You must publish to "AIR 3.7 For iOS".