I think the setting that you're referring to is the 'display ratio' which can usually be set at 16:9, 16:10, and 4.3 in a lot of games. I am not sure how you'd do this in Skyrim. If you're on a PC, there may be something in the .ini file. If you're on an Xbox, then I'm not sure. I know that the Xbox, itself, offers the ability to changes display ratios. Not sure if that would actually help in this case, if the game is programmed to ignore the Xbox setting.
That's not entirely what I'm talking about. I know theres a standard and widescreen setting on the dashboard, but say in call of duty or battlefield, you can bring in the arrows so it fits your screen perfectly.