Microsoft.AspNet.UserManager - is there a synchronous version of 'CreateAsync' - how do I add multiple users in a single shot?

I am trying to add multiple ApplicationUser types to the 'AspNetUsers' table in my MVC project but there is only an async version of method for adding new users via the UserManger<TUser> type. Where is the synchronous version for adding multiple users in a single shot? I am trying to do this in my override of the Seed() method for my custom database initialization strategy.
I tried calling .CreateAsync(); by putting it in a foreach() loop and just ignoring the return value but this doesn't work. Is there a corresponding version of .CreateAsync() that isn't asynchronous?
EDIT: If it's not possible to add multiple ApplicationUser types in a single shot then my next plan of action is to do it myself without the help of .CreateAsync or a UserManager wrapper object but I'll need to know how to hash the ApplicationUser passwords and also get a security stamp. What two methods would I call to get those field values. Are they public methods that I can even call?< ...