5.2.1-RELEASE and devd.conf notify statement

I seem to be attempting to configure an unsupported feature
here.

What I am trying to accomplish is a change in powersaving
mode of my wireless card (wi0) triggered by a change in AC
line status.  Reading /etc/devd.conf leads one to believe
that the use of a "notify" entry is the correct way to
proceed (there is an example at the bottom of the file).
The manpage however has no mention at all of a notify 
statement; only "options", "attach", "detach", and
"nomatch" are listed as supported.

Which is correct?  My entries using the notify statement
all appear to be inoperative.  I have copied the example
and changed only the "action" line.  I have tried both

action		"/etc/rc.wireless_powerstate";

and

action		"/bin/echo $notify >> /tmp/powerstate";

Neither seems to do anything at all.  The first is an
executable shell script that works fine when executed 
from the command line (rather counter productive if
that's what I have to do!!).

Since I do not know if devd continuously scans its 
config file (can anyone tell me if it does or does not?)
I also tried rebooting after making changes.  There was
no difference in behavior.

Could someone help me out here?  Is this a feature that
isn't actually implemented in 5.2.1-RELEASE and shouldn't
be expected to work?

Sean