In Office 2008, how may I set the theme color in conditional formatting using AppleScript?
tell format color of color scale criterion 1 of colorcellObject
set theme color to first accent theme color
end tell
This script through errors (set theme color object is not defined).

I have no experience with Applescript (using VBA in Windows myself), but I would suggest using the {[0-255],[0-255],[0-255]} codes for the RGB colors.
These can be hardcoded if you know the codes beforehand, possibly you could use a small section of your excel to apply the appropriate colors to and refer to those in your script.
For the script follow along the lines of this: AppleScript: set Microsoft Excel cell's background color