Automated Login to Password Protected Website that has Captcha

I advertise on a niche based password protected website that has captcha. The captcha images rotate among 7 images that are one word in length. I would like to automate the process of logging in, a few times an hours, because on this site it pushes your advertisement to the top of all listing. I've tried Website Watcher and set up multiple login attempts using all the known captchas time a minute apart but the site blocked me after only an hour. Stating the this isn't allowed. I need you to create a script or a plugin for the software Website-Watcher that will "recognize" or match the captcha from a known list and then login? If this is not possible, I need a bot or software that will accomplish this goal. Thank you for your time and assistance.