[ale] Howto suspend on power button press

[mdhirsch at gmail.com (Michael Hirsch)]

A while ago I had a computer that would suspend to ram when I pressed
the power button.  This rather surprised me, but was actually quite
nice, but I don't know why it did that.

I have a nice machine now and I'd like to be able to do that.  I've
been reading ACPI howtos, and getting almost nothing out of them. 
They seem to spend all their time talking about how to compile ACPI
into the kernel, but no time at all talking about how you control it.

Can anyone point me to a nice write-up of how to configure and use
ACPI assuming that it is already installed?

Thanks,

Michael