What I'd like to do is disable the function key on a keyboard entirely. We have devices that are in an environment where the Fn key is never needed and the "alternate" functions of the function key row (referred to as 'media keys' from now on) cause more issues than they solve. Case in point users accidentally disable the trackpad on the devices. Using function lock does not solve this problem because, in their environment, they eventually unlock the media functionality and hit various media keys causing support chaos. They also accidentally hold down the Fn key on the keyboard and activate a media key. The most viable solution is to turn on the original function key functions and disable the Fn key entirely.
One major caveat: a third party application can't be used.
One major preference: to not have to do this through the BIOS (should be able to be done remotely)
Best Answer
As said, it's not possible to remap the Fn key on most PC keyboards as it doesn't generate a scan code. You can only remap the Fn+key combinations which can be done by editing the registry key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout\Scancode Map
(except some keys that generate triple-byte scan code). Key mapping programs like SharpKeys or KeyTweak are in fact just does the heavy lifting of modifying the registry for youSo you can edit the mapping then extract the key to a *.reg file for use on all machines with the same keyboard. No 3rd software is needed
But the better solution is to persuade the IT department to allow the use of some 3rd party software like SharpKeys or compiled AutoHotkey scripts. After all, SharpKeys or KeyTweak is simply a registry-editing software and doesn't run any scripts, access the network or run in background. Just run it once and you're done, and more importantly SharpKeys is open source so everyone can verify what it does
Another way is to use Microsoft Keyboard Layout Creator and define your own mappings, but it may not work for all keys on the keyboard. After exporting the layout you can also use it for other PCs
See also Remapping via the Registry's "Scancode Map"