I came across a shot on dribble tonight, which had a wireframe with a nice background to it. I thought it was nice so I whipped up a quick Acorn script that will add a similar layer to your current image:
You can view and download the raw script on the AcornSDK project: Insert Drafting Paper Layer.jstalk
Side note: I actually wrote the script twice (you'll see two functions in the script that show this). The first time I did it by adding hundreds of rects to a new shape layer- but that seemed a little overkill. The second time I did it by drawing straight to a new bitmap, and then just passing a CIImage back to Acorn with it.