Right, first you need to open up the A320 folder and then go to your airplanes folder. Then go to an addon that has an A321 panel. Check it with Notepad, and check that it says:

alias:

Airbus_A321/Panel

Or something similar. If it says that, copy it to your addon aircraft's panel folder and replace the panel.cfg with the one you have just copied. Then go to a plane that uses the A321 sound and do a similar thing to the above. Only difference is this:

alias:

Airbus_A321/Sound

Then copy it and replace the previous sound folder in your A320 panel file. Then you need a thumbnail. I suggest that you copy an image from Google etc. and then save it in My Documents. Then go to your documents and open the image with Microsoft Paint. Click Save As, save it as thumbnail and change the file type to a .jpg format from the drop down menu. Then go back to My Documents and cut your new thumbnail (right click, cut) and then paste it in the Virgin A320 texture folder. Then move the entire A320 folder to your airplanes folder. And finally you can fly in FSX!

Hope this helps!;):)

This can be used to make FS2004 aircraft flyable in fsx. It works with most FS9 aircraft and you just need to find a different panel for the plane if it's not an A320/A321. PM me if you need more info.;)