The third page of your link wasn't on the server, so I'm not certain whether the poster was able to do it either.
The keyring will hold other keys as well, so I wonder if bypassing it is a good idea. Imagine that you also have an encrypted partition or have a passphrase to unlock your ssh private key. If the passphrases for these keys are also held by the keyring, then you would be seriously compromising security in the name of convenience. Imagine if you engage in on line banking, and the keyring caches your credentials. Someone stealing your laptop would be able to empty out your bank account. Consider changing when the wireless interface starts up instead from onboot to ondemand. I don't use Ubuntu, so I don't know whether you use an /etc/sysconfig/network/ifcfg-wlan0 file. From the man page for "ifcfg":
The following is a list of variables that can be put in the configuration file, with an
example in parentheses. * marks the default. For the meaning of suffix, see the section
Choose when the interface should be set up.
manual Interface will be set up if ifup is called manually (without option boot or
auto Interface will be set up as soon as it is available (and service network was
started). This either happens at boot time when network is starting or via
hotplug when a interface is added to the system (by adding a device or load-
ing a driver). To be backward compliant onboot, on and boot are aliases for
This mode is nearly the same as auto. The difference between auto and hot-
plug is that the latter does not make rcnetwork fail if the interface cannot
be brought up.
The interface will be controlled from ifplugd. At initial ifup only ifplugd
will be started for this interface. Then if ifplugd detects a link if calls
ifup again which finally sets the interface up. See also variable
Nearly like auto, but interfaces with this startmode will never be shut down
via rcnetwork stop. ifdown <interface> still works. Use this when you use a
root filesystem via network.
off Will never be activated.
See if the nm applet configuration has a similar setting. This will defer the asking of the passphrase until you decide to use wireless. If you don't use wireless for the session you may not be asked for it. I suspect that the bootup request is due to the wireless interface being started up on boot.
Or you could use ifdown/ifup style configuration to authenticate instead of a graphical network applet, and have the ifcfg file (or the Ubuntu equivalent). You would do this if you always want to use wireless and don't use the gui network applet to connect to other wireless networks. The wpa psk key will be contained in a root readable config file. If your system doesn't use an ifcfg-wlan0 file to configure wpa, you may need to manually configure a wpa_supplicant.conf file to contain the psk. The wpa_supplicant.conf file can contain entries for other networks as well.
Good Luck. Be sure you understand the security implications when trying to make things more convenient. A master key phrase that unlocks other keys is best kept only in the your head if you want to protect yourself against loss of your keys due to theft or online cracking.