
The auto boot option can be set true/false in the ILOM. From the -> prompt.
1. Set the auto boot to true/false.
-> set /HOST/bootmode script= "setenv auto-boot? false"
-> set /HOST/bootmode script= "setenv auto-boot? true"
2. Reset the system to apply the changes.
-> reset /SYS

You need double quotes to perform this:
set /HOST/bootmode script=”setenv auto-boot? false”
set /HOST/bootmode script=”setenv auto-boot? true”
Thanks Joachim for the corrections!