Lightroom Integrated: Workflow Phase II - Black and White in Photoshop CS4 and Photoshop Lightroom - page 97

Step 6: Split Toning
Lightroom features a very easy and powerful ability to split tone, which is to
apply two separate hues - one to the highlights and the other to the shadow
regions.
1. Within the Split Toning palette, grab the Highlight Hue slider and pull
slowly to the right.
2. Once you have decided upon a highlight tone, repeat Step 1 with the
Shadow tone.
3. Simply slide the Balance control back or forth to equalize the image to suit
your taste.

Tip:
While moving the Hue
slider, hold the Option
key. This gives a preview
of all hues at 100%
saturation and saves a
ton of time.