Go to C:/Program Files/Ubisoft/Eagle Dynamics/Lock On/ME and open the meinit.xml file with notepad. In that file, there is an entry for each aircraft, and in that entry, there is a "HumanCockpit = yes/no" option, and if you want to make an un-flyable flyable, you just change the "HumanCockpit="no" to "HumanCockpit="yes". The easiest way I found to do this is to get into the meinit file, then do a search (Ctrl + F) for either the type of aircraft you want to change, or search for "HumanCockpit", then you can just check what kind of aircraft you have found (by scrolling right a little bit, it's in the same line as "HumanCockpit" but a little farther down, under "name") and whether or not you want to change it. Hope that was helpful.
