Hi Catisfaction,
LifeisLike is correct about the method by which you can get the scrolling gallery HTML for your auctions, but I would also like to point out that you can configured your Auctiva account to automatically add the scrolling gallery to the listings you post through eBay while on the Free Tools plan.
If you would like to do this, you'll first want to mouse over the "My Account" tab within your account and select the "Acct Preferences" option under "Settings". You'll then want to select "Yes" from the drop down menu labeled "Append Auctiva Scrolling Gallery to my listings" and click the "Update Account Preferences" button below.
As long as you have this setting enabled and maintain a valid token, the Auctiva scrolling gallery should be automatically added to the listings you post directly through eBay shortly after they are posted.
-Mike