You can also use BaseHue Express which is a more global color changer but at the same time simpler to use. with UI Tweaker its tricky.... I just use trial and error. There are a few threads as well as the creator's website that can give you more details. (I'd look them up but I'm about to go out for the day sorry!
)
The reg edit is:
HKLM\Software\HTC\PHONE
Edit "hightlight color" and text color if you need to.
soft reset before changes show up... so its hit or miss if you get the exact results.
And the other portion of the dialer background is a png file that you can change if you like which is in your windows folder Dialer_Bkgnd_Port.png