I've noticed everybody is excited about this and asking about the technique, but nowhere was the exact process actually described. Here it is:

In Photoshop Elements 2.0, do this:
1) Select the portion of the image you wish to skew with the rectangular marquee tool.
2) Click Image, select Transform, click Skew.
3) Grab (ie. click and hold) the center point at top or bottom of your selection (not a corner point!) and drag.
Done!

In ArcSoft PhotoStudio 6, do this:
1) Select the portion of the image you wish to skew with the rectangular marquee tool.
2) Click the Transform button.
3) Click the Skew radio button.
3) Grab the center point at top or bottom of your selection (not a corner point!) and drag.
Done!

In both programs I would recommend that after Step 1 you actually create a new image (or layer) from the selection via Copy/Paste, rather than altering the original image. Then you can save (or copy) the results without affecting the original image file.

To read the earlier E-Sylum article, see:SKEWING - A TECHNIQUE FOR SIGNATURE IDENTIFICATION(www.coinbooks.org/esylum_v14n43a06.html)