Enhancing Input Field - Put The Selected Recipient Into The Encasing And Insert It In The "To" Field Box?

I'm trying to replicate a feature found in hotmail, facebook, etc. When you type or select a recipient from an auto-suggest box for your message/email that recipient's name is put into the "To" field box and is encased (usually a blue rounded corner box) with a X to the far right. If the "X" is clicked the recipient is removed.

How can do you put the selected recipient into the encasing and insert it in the "To" field box? If there are multiple recipients how are they differentiated? For example, if there were a ";" between the recipients the semi-colon would separate the values.