I think a good way to create ken ken problems would be to leave some totally empty cells.
I have posted an example here : http://www.sudoku.com/boards/viewtopic.php?t=14895
(sorry, not sure if there is a way to put a diagram on this forum as well).
It's actually numbers 163 and 167 of the master level of the iphone capcom kenken application, but with removing the unneeded squares.
Now whenever I solve a kenken, I can t help searching which cell infos I can avoid using
.