Abacus EZ-Scenery will not work in FSX.
Rwy12 can work with FSX. You can place default FSX objects that were migrated from FS9 (a fairly small list as compared to all the new objects added to FSX), as well as custom objects that either come with the (3) Rwy12 object libraries or others that were later created for Rwy12.
With Rwy12 you can place buildings and objects around your airport (or anywhere else for that matter). It cannot modify the airport , i.e., runways, taxiways, parking, navaids, etc. For that you need an airport editor.
The only airport editor I know of that will work without the FSX-SDK is Flight1's (payware)
Airport Facilitator X (AFX). There is a demo available at the bottom of the page, full function within 50 miles of Seattle I believe.
Dave
At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation. Igor Sikorsky
I intend to live forever....so far, so good. Steven Wright
You know....you can just rip up a to-do list.