A Visual basic Web Control for Automation

I am working on a web browser in visual basic.I need to know if the default webcontrol in Visual Basic is enough for the following.

I have the following inputs:

 1. User Agent="Mozilla blah blah"
 2. Javascript to be injected ="<script>doc.get['but'].click</script>"
 3. Url="http://foo.com"

The automation process is as follows.Use "User Agent" and Go to "Url", once page loads inject "Javascript to be injected" {This causes a button to be clicked:similar to using the console on other browsers}.

If the default webcontrol can't work with the mentioned inputs I would appreciate for suggestions regarding webcontrol libraries that can do the above. And if the above can be done I would love to see some examples of the code.