Everytime you refresh the source you will be prompted to enter the ticker symbol, it's not a one time setup. So if you wanted to look at a different ticker, you can refresh the source, enter the new ticker information and pull the data down. I would still consider this to be part of the "Tableau Interface".
You could certainly setup your own WDC to take a ticker and date range or even multiple tickers. The possibilities are really only limited by your development capabilities.
Thanks Tom for your suggestion.
I will take a look and let you know incase of any issues faced.