MGriffin-
That page does not have a place to edit it in the admin panel (in terms of making the look/feel different or changing different options). Skipper is right, you can download the page if you have full FTP access, and then you can make your desired changes.
Danilyn-
They do not get implemented. Essentially, what being marked custom does is that it makes your site not get any update patches/new version releases because anything you would have changed will get overwritten by the new update. It is not meant to be a deterrent. Some customers of ours have neglected to tell us they were changing the code and then were very surprised to find all the work they did was gone.
You can request updates though, if you are marked custom. If you have saved your changes, then you could just paste it back in there after your requested upgrade roles through.