Comment 4 for bug 719048

Well, the alternate CD only needs the one CD to install; AFAIK it doesn't need any further media for the install to complete. Please file a new bug about eject for discs if needed (using 'ubuntu-bug debian-installer' should help you there), then report the bug number here. Note that you may try to switch to a different virtual console (Ctrl-Alt-F2 for instance) and run "eject cdrom" to try to eject the device manually as a workaround.

In any case, WPA in d-i is not currently supported. It may be added in a future release (pending the work to be completed in Debian), here's the relevant Debian bug: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=550744 .