Hi and welcome to hak5 forums. Im not quite sure what you mean by your question and I dont know what makes you think the first 400 bytes does not store any characters as this is incorrect, however I have created a tutorial explaining exactly how to use this key table, I hope that you find it helpful :)
h2oh4x!
Tutorial link:
http://www.4shared.com/file/216272639/56f4...kdatabin_t.html