If reading Excel as a database you would use "Access LSLINK"
Access external means you are reading a file. I don't think it is possible to treat Excel as a file because the internal structure is complex.
In the past I have saved the Excel as a CSV or as a Tab delimeted file. Then I use something like
ACCESS External
USE &filename
BEGIN
DESCRIPTION free ,
Variables text 20
Organisation text 20
'July 2008' numeric 20
'August 2008' numeric 20
'September 2008' numeric 20
'October 2008' numeric 20
'November 2008' numeric 20
'December 2008' numeric 20
'January 2009' numeric 20
'February 2009' numeric 20
'March 2009' numeric 20
'April 2009' numeric 20
'May 2009' numeric 20
'June 2009' numeric 20
END
peek
read
... quit the access sub system
END