You mean making the user input his/her access token in the name field in Zorro UI? That would definitely work if the access token is forever which I think it is.

However I don't know if that is a practice that would be approved by Oanda...you see there are 2 kinds of access tokens, personal access tokens that you get when you develop an application for yourself and third party access tokens which you get when developing an application for many users. In the latter case, the application has to be approved by Oanda. Here is the documentation for that
http://developer.oanda.com/rest-live/authentication/