ExcelBanter - Bulletproofing a worksheet

SuperJas
I need to have these particular cells (6 cells) unlocked as these cells serve to gather input for the calculations on the worksheet. I would like to use worksheet input rather than forms to facilitate editing of just 1-2 cells at a time and to facilitate what-if analysis, goal seek, etc. I would like to protect the formatting (fill color, number format, etc.) in these cells, and I do not want users to enter any formulas, just constant values within a certain range which I can restrict through data validation or other means. I can create custom menus and toolbars to restrict those actions that are normally available, however I am unsure of how to restrict the entry of the myriad of keyboard shortcut keys which can accomplish most anything in and of themselves. I have worked a little bit with Onkey method of Application object, but ran into problems capturing the + key on numeric keypad (I can capture + key on regular keyboard) on my own notebook computer. I am trying to ascertain if my goal of making a "bulletproof" worksheet is even feasible

Thanks in advance for all assistance!