|cells(i, 67) is a way of writing "BO"i (where i is a number between 2 and 100)|
cells(i, 68) is therefore a way of writing "BP"i (where i is a number between 2 and 100)
Yes it can be assigned to a button. On excel 2003, go to Tools/Customise...
On the "Commands" tab, go down to macros, drag "custom button" up to the toolbar. Click on it once you've closed that, and you can assign the macro to it.
It won't work in another workbook though. In fact I can't remember how to make it appear in only one workbook. I never use them, prefer to use Alt-F8. DerbyDad will know I'm pretty sure!