It is possible. However, to do that, you need the original files, such as those available on freeflightdesign.com. You can also look here in the Orphans section. You also need a design program. For FS9, you will need either G-Max or FSDS2. There are tutorials and plenty of freeware tools that allow you to convert old design files so that they will work in G-Max or FSDS2. If you are looking for tutorials and tools, you can find them all on this website.

This is very time consuming and requires plenty of concentration. So, if you're looking for a quick fix, the answer is no. If you are willing to put in the time and energy to do the job right, then the answer is yes.