Is this for an automated process or is a user involved?
I'm not sure what you mean "things to learn here; login to mojoPortal, fill in the form field, push a button, scrape up the status reply..."
For automation I would not go for any approach with screen scraping or trying to automate interaction with the web ui. Not sure if thats what you meant.
I would use web services and be sure and use SSL so that all communication is encrypted.
To handle the automation/schedule the calls to the remote service I would write a Windows Service which is pretty easy in .NET
If its not automated but submitted by a user I would use a form and post to the web service, again always using SSL.
Hope it helps,
Joe