You can not simply pass a token to a webview: the webview does not allow this. (at least, the last time i looked at it)
What you can do is pass a parameter via a url. If you can make the destination application accept the url parameter as login token, then you have a plan.
I have implemented and gone to production with this once, so it is possible. But it wasn't easy and it was not in a Mendix application.