The icons are all situated in files of the 3DB nature if I remember rightly. You can extract the image used with UTF, saving it as a tga I think (see Ospreys Icon tutorial for extrating images from these things)

Simply replacing the image would probabily do it, and the files are located here:

C:\Program Files\Microsoft Games\Freelancer\DATA\INTERFACE\HUD

There is more in neuronet as well I believe, smaller icons, little windows etc. Its been a few years since I rooted through them - and the mod you saw it in would have been the Freeworlds mod.

yea, these is a whole bunch of icons that are being unused. I am gonna see if i can make a list of all the images that can be extraced from the files. Because I have not played Freelancer in a while, I am unsure as which image extracted is image in the game. I am hopping that if I create an list of each file name, accompanied by the image extracted more regular players will be able to recognize where that image is situated in the game.

well back to organizing lol...