If you haven't already, go and download
Locotool. Download either locotool_v0.4.3 or locotool_v0.4.3b (not sure if there's any difference). Unzip the files and put them wherever is most convenient, in your Locomotion folder for instance.
You can now edit any file in the game's Objdata folder. Drag and drop the file (look for 777.DAT) onto locotool.exe and it will create a folder of images and an .xml document. Don't mess with the images folder. Open the .xml in Notepad and you can make any edits you like.
To change the name of the file, find these lines in the code.
Code:
<unknown name="field_11A[15]" size="1">3</unknown>
<unknown name="field_11A[16]" size="1">13</unknown>
<variable name="numsnd" size="1">2</variable>
<description num="0" language="0">Boeing 777 (L)</description>
<description num="0" language="1">Boeing 777 (L)</description>
<description num="0" language="2">Boeing 777 (L)</description>
<description num="0" language="3">Boeing 777 (L)</description>
<description num="0" language="4">Boeing 777 (L)</description>
<description num="0" language="5">Boeing 777 (L)</description>
<description num="0" language="9">Boeing 777 (L)</description>
<description num="0" language="11">Boeing 777 (L)</description>
Yours will have different names because mine are heavily modified, but where it says "777" change the name to what you want it to say. Be sure that you don't mess with any other parts of the code.
Once you've made you changes, save the file. Then drag and drop the .xml onto locotool.exe and your changes to the main file will be saved.