Wondering how to do this

Hello! I could not find a place more suitable for this question, since I am not sure what language it would be done in. This is more of a "how do I start" with this.

What I am wanting to do is create maybe a plugin, or 3rd-party app that will automatically click to select items on a web form.

The situation is that my company uses a 3rd-party company for business information, but they do not have a "select all" button. It requires that we designate someone to sit and click item after item on this site, sometimes demanding 1000-2000+ items be clicked. It can take hours. If there was some way to either A. write a small addon that can do the clicking with some prompt, B. get a recommendation if there is already something that anyone knows of that can do that, I would greatly appreciate it!

EDIT: I have some coding experience, but more importantly, a willingness to learn. I can grab some books, or check out some web sites to learn how to do this task, which I would hope would not be too extremely complicated. Thank you again!

Well there are three approaches:

1. Write a program that downloads the page, works out the form entries and submits them all checked. That wouldn't require (or even permit, depending on how you write it) human interaction. Recommended language: perl
2. Write a program that sends <enter><tab> repeatedly to the active window (browser). On windows, vb6 would be ideal for this. I have NFC what scripting languages would do this easily because i've never needed to do this.
3. Write a firefox plugin (javascript) that does it.

Thank you for the fast reply! I will probably go the VB6 route, as I have a good idea on how that would be done. I don't know why I had not thought of that before! Thank you