If you don't mind playing with RGB values, you can set whatever color you want in the INI file. Make a back up first just in case you mess it up. Note, this is from Fallout 3, New Vegas should be the same, or similar.
iSystemColorTerminalRed=33
iSystemColorTerminalGreen=231
iSystemColorTerminalBlue=121
iSystemColorSystemRed=26
iSystemColorSystemGreen=255
iSystemColorSystemBlue=128
iSystemColorMainMenuRed=199
iSystemColorMainMenuGreen=255
iSystemColorMainMenuBlue=165
iSystemColorPipboyRed=26
iSystemColorPipboyGreen=255
iSystemColorPipboyBlue=128
iSystemColorHUDAltRed=255
iSystemColorHUDAltGreen=67
iSystemColorHUDAltBlue=42
iSystemColorHUDMainRed=26
iSystemColorHUDMainGreen=255
iSystemColorHUDMainBlue=128
My way was easier IMO. You just changed one string of numbers
Edit: http://www.gamesas.com/index.php?/topic/1070653-how-to-change-the-hud-and-pipboy-colour/page__p__15561700__fromsearch__1entry15561700