Using Paintshop Pro 7 Mask
These are the two images I used for this tutorial. You can right click and save both images.
Open both images in Paintshop Pro. See Below

Click on the image of the actual mask. File named is masktut1.jpg then go to Mask > New >From Image

From this menu choose the mask in the drop down and click on source luminance.
File name is iezombienetmaskbyheidi3.jpg
Finished Image.

You can find more of my mask here:
http://iezombie.net/category/mask/