1.3 will be out soon fixing this problem hopefully.
It works by just renaming your current (ie, the files before you start randomroll) index, redirect and error.php to index, redirect and error.php.orig, and then RandomRoll will proceed to just softlink its own files there, as usual. Then when you disable RandomRoll it unlinks its files and renames your files before you started randomroll back to the defaults, and then happy days.
If their are any more problems, bugs or something i'm missing please reply here so i can fix them hopefully before the release. I am sad to say that there is no 'easy' way to add rolls yet, as im really busy as most of you are. I will try to do it as I know it would make life easier for some of you (especially barry with his nice custom rolls ).