Sorry, Bret. I misread the poster on your last message.
I found an answer to my problem. Here is a post I got on MacScripter:
Hi
In office 2004, if you use a text argument for the range address, you must
specify the address in A1-style notation
(you cannot use R1C1-style notation). For more information about how to
reference cells and
ranges, see the topic "How to reference cells and ranges." in
Excel2004AppleScriptRef.pdf
Open this Scriplet in your Editor:
tell application "Microsoft Excel"
activate
set formula r1c1 of active cell to "Comm"
select (get offset active cell column offset 3) -- +3 column
set formula r1c1 of active cell to "Commission—GSA"
select (get offset active cell column offset 1) -- +1 column
run script alias "OS X
Boot

OCUMENTS:AppleScripts:SigTaxScripts:SigCheckNum.scpt"
end tell
or
Open this Scriplet in your Editor:
tell application "Microsoft Excel"
activate
tell active cell to set {RowNum, ColNum} to {first row index, first
column index}
set formula r1c1 of active cell to "Comm"
set ColNum to (ColNum + 3)
select cell RowNum of column ColNum
set formula r1c1 of active cell to "Commission—GSA"
set ColNum to (ColNum + 1)
select cell RowNum of column ColNum
run script alias "OS X
Boot

OCUMENTS:AppleScripts:SigTaxScripts:SigCheckNum.scpt"
end tell
The script that Jacques sent worked perfectly. You might try posting your
question there as well.
Hope that helps,
Tom Carlson