A custom tool sheet can be created by editing or creating an xsl file. This file is a stylesheet that displays the xml data created by Camworks. There are limitations to the data that is passed to the xml file by Camworks, not all variable fields that exist in the Camworks dialogue windows will be available in the xml. The xsl stylesheet also has limited functionality in regards to data manipulation.
A great tool to view the xml data file is the application 'XML Notepad 2007', there might even be a more recent version.
There are also xsl editor applications which would be helpful in creating and editing the xsl, both the xml and xsl files can be opened by a text editor.