The logo is lit with a reddish hue (the User Guide says this is orange) when the router powers up in its factory default unsecured state. The instructions in the WRT54G's User Guide just say to press the SES button. But there is an approximately 8 second pause between the button push and three seconds of no light, followed by the rapid white flashing backlight that indicates the router is in SES search mode. We found these delays confusing and ended up pressing the button repeatedly the flashing light started. Fortunately, this didn't seem to mess anything up.
Linksys makes the SES button on its client manager software easier to find (Figure 5), displaying it prominently no matter whether you've selected the Link Information, Site Survey or Profiles tabs. After clicking on it, and the Next link on the next screen, a "Searching the wireless network" progress bar pops up, which soon subtly changes to "Connecting the wireless network" if all goes well (Figure 6).
A successful SES negotiation is indicated by the Congratulation (sic) screen (Figure 7), which conveniently displays the SSID and WPA-PSK key used. Given that SES employs essentially the same methodology as AOSS, we were surprised to see the SES completion message in about 45 seconds, just about a minute less than AOSS took!
By the way, both the Buffalo and Linksys routers display the generated SSID, encryption settings and keys in cleartext in their admin interfaces. You'll need these to connect non AOSS / SES clients into a wireless LAN secured by either technology.