automatic power on possible?

Most modern motherboards supports the timer based automatic power on
via BIOS settings. With linuxbios this is not(?) possible. There is a program
for linux, called nvram-wakeup, to set the wakeup time in nvram or rtc. But
especially for the K7SEM or EPIA boards a reboot is needed after it, so the
wakeup settings can take effect.
Does anyone know what the BIOS is doing what linuxbios does not?
Perhaps it can be done in a program?

Thanks

Thomas Wehrspann