You might like to have a look at Adobe Fluid Mask Plugin. It is a download costing $129US.
I used to do deep etching using a copy camera with registration pin masking on both Kodak Kodalith Type 3 and Kodak Pro Copy film. Physically removing backgrounds on paper prints using scalpels and painting out negatives using colloidal graphite and Dupont Gold Tape.
The Fluid Mask Plugin is certainly the go nowadays. You will find the Plugin download links on the Adobe Photoshop site, and also on the Adobe Lightroom 2 Tutorial site.
http://www.photoshopsupport.com/tool...luid-mask.html
Warren.