Check out the content of vga.c (in dlls/winedos), you have most of the code you need. However, int33 mouse hide/show should cooperate with the vga layer.
OK, here's a first draft at a patch. Created with reference to my old copies of Ralph Brown's Interrupt List.
Cheers, Chris
___________________________________________________________ALL-NEW Yahoo! Messenger - all new features - even more fun! http://uk.messenger.yahoo.com