I just updated the stock Excel CAT tool to use RTD instead of the now defunct DDE. This only works on Excel for Windows unfortunately. You can go download it now from my Google Site under Released Tools in the Donors Only folder. If you already donated in the past you can use your password to access it. If you want to become a donor (or throw me some more coin) you can do so by clicking the Donate button:
If you want to learn more about the CAT, the original blog entry is found here.