VKB files are generated from XML documents using gen_vkb (from the libimlayouts-generator_1.5.6-1_i386.deb or libimlayouts-generator_1.5.6-1_armel.deb packages -- see here)

The best bet (at least this is what I did to develop a Fitaly keyboard), is to use decode_vkb to decode an existing VKB file into a corresponding XML document, then edit it using your favorite editor, and compile it back into a VKB using gen_vkb (above). In your case you will need to de-compile, copy the XML file to windows, edit it, then move it back to the tablet, the re-compile it there. See this thread for the steps/instructions.

The "Virtual Keyboard" section of this document provides some basic documentation, but overall, you are on your own...

I had my Fitaly keyboard working on OS2007 but I am having problems with OS2008 where I cannot centre the characters in their key boxes. I opened a bug, see here.

Hope this helps,

Robert B.