ASP.NET Identity - WEB API to generate a Token

Hello,
I’m writing ASP.NET Identity WEB APIs which will get integrated with variety of user interfaces such as web, portals, mobile. One of the key tasks is that before we activate the user accounts, we need to send a token to the user on their email address. Users will receive an email and they will click on the URL. This URL will have token embedded within it. That will take the control back to the Web Server hosting User Interface. The client User Interface will then consume another API and send the token in question and the user details back to the WEB API server, where we will validate the token, user details and activate the account. So, the authentication will not be cookie based, because there is no UI here. One of the key tasks is to generate the token within API. So can I generate a custom token using GenerateUserToken()? or is there a nicer way doing this? The trouble is I don't own the UI, so I can not initiate any changes on the UI; hence, I be ...