Is there anyway for this to be done?
Not with what the HTML Agility Pack (HAP) library provides - not directly.
The HAP is great for getting a single page and parsing it, but it is not designed for continued interactions. Things that are missing are cookie management, JavaScript interaction and more.
In order to login you probably need to send an HTTP POST to the server, including the data you want - the HAP can't help with that.
You will need to use a class like WebRequest
to make the post - I suggest looking at fiddler and using it to see what the request should look like and constructing it accordingly, though that may just be the first step.
You may want to investigate the use of web automation tools such as selenium or WatiN instead.
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