Okay Joe, managed to get AdBlock installed without too much trouble, so here's how I did it.
The Latest version of AdBlock (v3) wouldn't load with your version of CD so I had to download an older one (v2).
The one I downloaded is AdBlock-v2.66.0.zip, available HERE. (You could try a later version if you want to, but like I said, the very latest wouldn't work).
When you have downloaded the zip file you'll need to extract the contents, I'm sure you know how to do that but if not, right click on the zip file and select 'Extract all' from the menu...
...after you have extracted the files you should see another folder with the same name but without the .zip extension. Make a mental note of where this folder is...
Next, go to Comodo Dragons extensions page, and check the 'Developer Mode' box [1]. Then click the 'Load unpacked extension' button [2] and navigate your way to the folder I mentioned previously. Click on the small arrow to the left of the AdBlock-v2.66.0 folder to open it and select the first folder beneath it, named adblock. With that folder selected, click the OK button at the bottom of the dialogue box.
...if all went well the AdBlock extension should now be installed into CD and you can uncheck the 'Developer mode' checkbox.
Good luck. : )