I was very exited to find out that Russell Brown made his Watercolor Assistant action/panel Open Source. If you download the files from http://russellbrown.com/scripts.html, you can reverse-engineer his steps. AND (eee-ha!) he includes the pattern for the paper and the .tpl files for the brushes. Watch his demo and it'll be pretty clear what's going on.

The step that makes his script incompatible with CS5 and below is running the image through CS6's oil painting filter and using the oil painting to make the pencil sketches. BUT that step isn't critical - you can use other methods described in the forum and in many places on the internet to make the pencil sketches. If you have CS4 or CS5, you can still get the Pixel Bender plug-in from Adobe at http://www.adobe.com/devnet/pixelbender.html (look for the "Archived Downloads" section on the left side of the page). Be aware that the oil paint filter uses a lot of resources so it's best to make a flattened smaller copy of your image, run the oil paint filter and resize the "oil painting" to the original size of your image.

Reverse-engineering the panel gives you a lot more flexibility when it comes to making a painting. One more hint - if you hold "command-opt" (Mac) or control-alt (PC) while saving an action, you'll be presented with a dialog box that saves the action as a text file. So if you've got a lengthy action to reverse-engineer, you can generate a text file, which is a lot easier to read than trying to keep track of the steps in the Actions panel.