Just about anything is possible. I control my ham radio with Excel
and, at the same time have it talk via a hardware speech synthesizer.
There are many, many books  in all big book stores.
OR
Google on "Visual Basic for Applications" +Excel
Or try these
http://www.support.microsoft.com/
msdn.microsoft.com/.../en-
us/sdkintro/sdkintro/devdoc_platform_software_development_kit_start_page
.asp
pubs.logicalexpressions.com/Pub0009/LPMFrame.asp?
CMD=InfoDetail&ID=3
http://www.tek-tips.com/gfaqs.cfm/pid/707/fid/2112
www.microsoft.com/.../CH001H211#CH001H211
http://www.j-walk.com/ss/excel/index.htm