The screen cap above shows the ‘writing area’ for HWPen. You need to enter letters within the left half of the work area, and numbers on the right. Because it integrates with the native text input of the iPhone, HWPen is available anywhere you would normally use the keyboard. It even works with the iPhone's auto-complete function, so you can start to type a word and hit the spacebar to pick spelling suggestions.
The software application can be downloaded from Installer.app. Then one can go to “Sources,” click on “Edit” and “Add” a new source: http://iphonecake.com/src/new
Refresh the sources to locate HWPen in the iPhoneCake packages. Install the software and restart your iPhone. After you install you will see a writing area making the standard keyboard vanish. The application is currently in beta and is also available for the Palm OS platform.