I love this particular technique so much that I worked out another way to accomplish it that doesn't require swapping around files in and out of bitmap mode.

It's going to be the subject of an upcoming episode of my podcast, most likely episode #4.

The short version is: I make a layer with a grayscale area, like the one S. John uses in the first part of his tutorial. I put a Pattern Fill/Adjustment layer on top of that and group it with the grayscale layer, then use the Underlying Layer Blend If slider in the Layer Styles menu to make the pattern vanish from the white areas of the grayscale and become darker over the black areas. Then I put a Threshhold Fill/Adjustment layer on top of that to turn it from grayscale into pure black & white, with the lines thickening and thinning out.

The thing I like about it is, not only do you get that S. John woodcut look, but if you paint (or dodge/burn, or whatever) onto the grayscale layer, you can see how the woodcut effect looks in real time.

It's how I created the rippled lines on the water on my Foster's Meadow map.