Add class to ember link-to

I try to build a link to a nested route and want to add a class to this link (for twitter bootstrap) The result should something like this: ``` < a href="/#/rents/42" class="btn btn-primary btn-small">do something< /a> ``` First try: ``` {{#link-to "rent" rent}} ``` gives me a link to the ressource but I cannot specify a (css) class. In the docs I see that only the title attribute can be specified Second try: ``` < a href="/#/rents/{{rend.id}}" class="btn btn-primary btn-small">do something< /a> ``` is also a bad idea, because Ember will add its helper tags [for automatic updates] in the href. So what can I do?