I know that is what you said and I have a few options when I do rerun the installer. I can Do a new install which installs a new instance (not what I would think I want), Upgrade previous (which I would expect if it sees it installed would just upgrade it), Change exissting (My best bet on what to do) Or complete reinstall.
When I choose reinstall I have a list to what I want to reinstall. I didn't get a feeling that it would remove things like the IIS Aliases if I don't check it. Instead it would keep what ever was already there and just install what you have selected. So I didn't feel that checking components other than selfservice database and installing would do what we want.