Hi eyedocakes,
This is doable, but it will require recreating all of your eBay listings in Auctiva. Here's what you will need to do for each listing:
1) Recreate the listing using Auctiva(everything from the title to the template is necessary, but there is no need to fill in the shipping and checkout section) and save.
2) Go to your saved listings page, click the box next to the item, and click the "Get HTML" button.
3) Copy the html in the pop up window that appears.
4) Go to your My Ebay page and click on the item you just recreated in Auctiva
5) Click "Revise your Item", then "Edit Description"
6) Click the "Enter your own html" tab on the description editor.
7) Paste the copied html in place of the esisting html and save your changes.
I hope this helps=)
-Mike