http://thread.gmane.org/gmane.os.cygwin.applications/16914

Please consider the following patch to setup. (I tried to follow the 
patch submission guidelines, please correct me if I missed something).

Note that the new commandline options do *not* override the settings of 
a currently existing installation. I chose this behaviour because I'm 
unsure what the effect would be. It would be easy to change this,
though.

The output of setup.exe -h (to the logfile) becomes:

 Command Line Options:
  -D --download                          Download from internet
  -L --local-install                     Install from local directory
  -s --site                              Download site
  -R --root                              Root installation directory
+ -t --text-mode                         Use text mode mount for root
directory
+ -c --current-user-only                 Make cygwin available to the
current
+                                        user only
  -p --proxy                             HTTP/FTP proxy (host:port)
  -q --quiet-mode                        Unattended setup mode
  -h --help                              print help
  -l --local-package-dir                 Local package directory
  -r --no-replaceonreboot                Disable replacing in-use files
on next
                                         reboot.
  -n --no-shortcuts                      Disable creation of desktop and
start
                                         menu shortcuts
  -N --no-startmenu                      Disable creation of start menu
shortcut
  -d --no-desktop                        Disable creation of desktop
shortcut
  -A --disable-buggy-antivirus           Disable known or suspected
buggy anti
                                         virus software packages during
                                         execution.