The book, The Hidden Power of Photoshop Elements 3 has several tools
that might meet your needs. I believe the author sells them separately.
Do a web search for "Hidden Power". I think the URL is
hiddenelements.com, but don't quote me on that.
A luminosity mask is just a grayscale version of the layer itself loaded as a selection. Photoshop has a simple key combination to load the luminosity mask. Elements does not. You can, however, get the luminosity mask in Elements with just a bit more work.
If your layers palette isn't open, open it so you can see what you're doing. Begin by making the layer whose luminosity mask you want to load active. Let's call this the "base" layer to make the discussion easier to follow.
Create a levels adjustment layer. Don't make any changes to the levels, just click ok. This will create a levels layer immediately above the "base" layer containing a layer mask. Click on the "base" layer in the layers palette to make it the active layer again and then press ctrl-A to select the entire image and then ctrl-C to copy the image.
Now press and hold the alt key and click on the small white rectangle in the levels adjustment layer in the palette. The image should turn white as you're now editing the mask. Press ctrl-V to paste the image into the mask (you'll get a grayscale image). Press alt and click on the mask rectangle again to end editing the mask.
Finally, press and hold the ctrl key and click on the levels adjustment layer (PSE4 will need to click on the mask thumbnail) -- This will load the luminosity mask. Leave the selection active.
You're done with the adjustment layer, you can delete it if desired. But, if you keep it, you can reload the luminosity mask later if need be. You also have the option of saving the selection. Your choice.
Since you have Photoshop CS, you can easily create an action for Elements to do this and execute it from the effects palette. You'll need to create the action and a thumbnail image. For instructions see http://www.cavesofice.org/~grant/Challenge/Tools/Create.html When recording the action, you can use the standard key combination to load the luminosity mask and it will work when executing the action in Elements later -- you'll have a one step action.
The action and thumbnail will need to be placed in an appropriate PSE directory. See http://www.cavesofice.org/~grant/Challenge/Tools/HowtTo.html for a description of how to install Grant's tools. You would do basically the same thing for yours. You don't need a separate directory for each tool, if you have Grant's tools, for example, you can install yours in the same directory.
Barbara Brundage had a good explanation for how to create your own actions for Elements also but I've misplaced the URL.
Thank you for your method and the tip to create an action.
Thank you for your tip on getting the action into Elements. This was interesting as I had to slightly amend your instructions as my action created a blank psd image on my first attempt; the action requires two images to work on. I just created a "copy of Origional.psd" and used that together with "origional.psd" and all is now fine.
Barbara's actions instructions are very good and complementary to a rather more technical piece I did on the same subject...mine has more in the way of troubleshooting, and hopefully it isn't necessary for most cases. however, if you have tried and are having trouble, it might help:
I'm not sure I should keep coming to this site. It costs me too much money:-)
Last week I was in a well known London book shop, Foyles, when Barbara's book "Photoshop Elements 3 The Missing Manual" was purchased and yesterday my wife was perusing Amazon when your book "The Hidden Power of Elements 3" was put in the cart.
I now have plenty of reading; plus the link you have just given!