A quick update on this issue...

I exchanged emails with Harmony Support and finally followed up with a phone call today. boblinds is quite correct: Harmony Support is excellent.

I'm thrilled to say Harmony Support has resolved the problem - a tweak to their setup software now allows a clean setup.

Here are the steps need to correctly configure the power setting for the Outlaw 990:

From the Harmony Report User Home Page, find the Outlaw 990 device and click on the "More Options" link. This takes you to the Device Options page for the Outlaw 990. Click on the "Adjust power settings" link. This will take you into the device setup wizard.

1. Do you want to leave your Stereo Receiver on all the time?
Choose: I want to turn off this device when it's not in use

2. How do you turn your Stereo Receiver on and off with your current remote control?
Choose: A button on the remote for On, and a different button for Off

3. Select Power On Command
Choose: Use these infrared commands: -None-

A big warning will appear: No command was selected. Are you sure? Blah Blah Blah
Click the "Yes" button.

4. Select Power Off Command
Choose: Use these infrared commands: PowerOff

Proceed through the check, download to your remote, and test.

Optional: You can also speed up the power on sequence for any activity by decreasing the Power On Delay for the Outlaw 990. Since there really isn't a power on command, this could probably be set to anything... 500 ms works just fine for me.