grissiom,
Is your user a member of the power group? You shouldn't be getting those rejections if 1) you are in the power group, and 2) you're using the hal.conf that I pasted above (with the edit later in the thread).

One more bit... I just pushed a (hopefully) final version of the hal.conf based on some feedback from one of the hal devs. Rather than posting it here again, I'll just link to it:
http://slackware.com/~rworkman/hal.conf.txt

Thanks rworkman! After add myself to the power group, powerdevil could do CPU scaling~ Thanks.

It works!
Thanks Robby!

Thank you, everything works perfect!

It worked for me too. I now have frequency scaling enabled.

Thanks Robby

Thank you!!!
It work for me too :)

I hope you guys are still following along, because it worked, all right. It worked TOO well.
In my first set of tests, I somehow missed the fact that the config was wide open; in other words, it was TOO permissible.

I've now fixed it, and I have a new "hopefully final version" at the same location. Be sure to update it. http://slackware.com/~rworkman/hal.conf.txt