I need to implement a scheme for acquiring a
workbook/spreadsheet password for both storage and
retrieval of a file from a dongle. Is there a way to
intercept the Excel built in functions for doing this and
replace them with my own code? I was able to do this for
Adobe pdf documents by creating an Adobe Add-In that
replaced the standard product functions. I don't know if
Microsoft office products (e.g. Word, Excel, Access,
etc.) allow this capability.

If this can be done, then what Microsoft tools will I
need to acquire (e.g. Office Developer, Visual BASIC for
Applications, etc)? Can you point me at any
documentation that might save me time?

Is there a recommended solution that would be version
independent (i.e. supported on Excel 2000 as well as more
recent versions)?