Grid Click Event?

Hi,

Does anyone know how to detect a grid click so that a value can be populated.  The scenario I have is how to efficiently enter data into a tally sheet:

This is what I would like to accomplish:

1. User enters number of rows in the form header (for the above example 16)
2. 16 rows automatically appear in the grid beneath the header with the layer prepopulated 1 to 16
3. The user keys the 8 in the first cell, row 1
4. They then are able to just mouse click all the cells in the grid that should be 8
5. next, the user keys the 9 in the second cell row 2 and goes through the same click to populate process.

I know how to do all of the above except detect the mouse click and then populate the last value keyed (step d).  Any ideas.

Some of the tally sheets have lots of 3 and 4 digit numbers with high levels of commonality so the whole user keying experience is rather horrendous.

Also, what about Optical Character Recognition (OCR) for a tally sheet that looks like the above?  Anyone done anything along those lines?

Thanks heaps in advance.