Those pictures are in a file called fsmplane.wsp, which is in turn located in the WSPRITES.CDF file.
To edit the pictures:
1. Extract fsmplane.wsp from the cdf using CDFRW.EXE
http://www.sandbagger.uk.com/CORD/files/misc/cdfextractor.zip2. Extract all the files from fsmplane.wsp. Mr. Jelly made an excellent utility for this process, PM me with your email and I will send it to you.
3. Create a new image of the plane you want to use. Make sure it is 148x100 pixels in size. Find the name of the picture you are going to replace; i.e., if you want to replace the P-38H, it is FSMPLANE000.RAW; ssve your new image as a raw file and use this name.
4. Using Mr. Jelly's utility, repack the fsmplane.wsp.
At this point you can load it into your EAW directory and the game will use your new file instead of the old one. Or, you could repack it into a cdf, and use the new 1.28c file system. Additionally, if you are an OAW user, you can set up a folder there that will load your special plane set as well as the needed files ( the file you just created, new FM/DM, skins, etc...)
If you are going to mess around with screens, you should have a copy of Pilot Officer Prune's "Working With EAW Screens" notes. I can send you a copy....
Cheers!