Before I start explaining the pencil trick I want you to know that preferably you should adapt the parallel method. This is because the parallel method is by far the most popular way for 3D viewing. However, I am sure you want to be special and therefore different. So go ahead and learn the cross-eyed method. Frankly my dear, I don't give a damn.

Surprisingly, for the pencil trick you need a pencil. Hold the pencil between your eyes and the picture. Now focus on the pencil. This way the picture, which is now on the background, should become blurry. After some time the 3D image should appear. Again, this is a hard way to see a stereogram and it is harder to memorize the look than with the parallel viewing. This could mean that if you get used to the cross-eyed method you might always need a pencil.