I don't know exactly the top of my head and I don't have time to check at the
moment, but to find out if it's possible there are two places to look. The
first is the MS Excel COM object, which ColdFusion can interface with through
the <cfcomponent> tag. I would instantiate an Excel COM object and look at the
method listing (just <cfdump> the variable) and see if anything looks
promising. That is the most likely candidate.
Failing that, I would check out the Apache POI HSSF spec to see if they make
any methods available to do it. POI is included with ColdFusion MX, so it's
there to use if you need it. I consider it unlikely they have a method for it,
but if you look in both places and can't find anything, then I would feel
comfortable saying to your manager that it's not possible.
Hope this helps.