From DD-WRT Wiki
In order to get the SES/AOSS/EZ-SETUP to work, you must have Reset Button ENABLED, located in the Administration -> Management section
 Turning on/off wireless
You can turn on/off the wireless transmit of your router by pressing this button. Ofcourse before that you have to enable the service for that. Therefore go to Services -> Services and tick Enable at the "SES / AOSS / EZ-SETUP Button" group
 Run script when button pressed
You can also run a script when the SES/AOSS/EZ-SETUP button is pressed, therefore have a look at Script types. **Note:** You must have "Use this button for turning off radio" disabled (see section immediately above)
 Example to test custom button script
The following instructions will create a script that will flash the DMZ LED 10 times when you press the SES/AOSS/EZ-SETUP button.
Type in the following commands:
Make a file blink.sesbutton with the following contents (e.g. "vi /tmp/etc/config/blink.sesbutton"):
for i in 1 2 3 4 5 6 7 8 9 10;do gpio disable 7 usleep 50000 gpio enable 7 usleep 50000 done
chmod 744 /tmp/etc/config/blink.sesbutton
Now when you press the SES/AOSS/EZ-SETUP button the DMZ light will flash 10 times.
Pressing the AOSS button on a WHR-HP-G54 while booting may brick the router.
See http://dd-wrt.com/phpBB2/viewtopic.php?t=11658 for more info
There is also a risk that it will break the radio on the WHR-HP-G54 without bricking the router.
"See http://www.dd-wrt.com/phpBB2/viewtopic.php?t=60827 for more info"