Rwy12 and EZ-Scenery are not gonna help you in this case. You will need to the gmax gamepack sdk provided by Microsoft. It has detailed intructions on how to model a landable platform using only Gmax. You will also need the bgl compiler found in the bglcomp sdk in order for the conversion process to be completed.

But if you are just looking a pre-modeled landing plaatform, then you might wanna check the library objects list found in the bglcomp sdk. However, you will need to the instructions included in the SDK as well. Either way, you need the SDKs. You also need the makemdl sdk if you have not yet installed it. You can find them here:

http://www.microsoft.com/games/flightsimulator/fs2004_downloads_sdk.asp

Good luck.