beside crap quality of your quoted source (where you could find way better in few sec just by googling), you can see even reason of your problem right in your quote:
_htmlCode = htmlCode; // html code must not exceed 8192 bytes
L2 client assemble html string from exactly 3 showBoard packets before rendering whole window update in game,
so all you have to do with your crap source, is to chunk your string to 8kb parts and pass them to ShowBoard with IDs: 101,102,103
Im entirety amused how clueless you look to be, and yet bother with some altB htmls. Should we expect new 100% retail like server in upcoming week? :D