Remapping function keys can be achieved through the config.xml file or meta-tags within the app. This is covered in the PocketBrowser documentation located in the documentation folder within the installed folder on your Windows PC.

For example:
In the following example the browser will disallow the user from pressing left to advance to the previous character in a textbox, however the function 'keyTest' is called for both left and right keys.

You can find this in the "Key Handling" section of the documentation.