delete 400k photos iMacros script

I need a iMacros script that allows the user to delete all posts on a blog.

Currently I am using Xkit (check it out, might be helpful), a chrome extension with lots of handy features.
I installed their Mass+ extension, which allows you to select 100 posts and then delete those.
Anyway, I get a pop up asking 'are you sure you want to delete the selected photos', which Imacros can't seem to record when I click on 'ok'.

Selenium, Javascript, tampermonkey scripts, can deal with the dialog. I'm quite sure iMacros can accept dialogs too http://wiki.imacros.net/ONDIALOG

http://www.seleniumhq.org
https://tampermonkey.net/scripts.php
https://greasyfork.org/en
http://userscripts-mirror.org/
http://www.greasespot.net/