What DOM element to specify with a Directive?

What DOM element to specify with a Directive?

I'm using Soda (node.js) w/ Selenium RC to automate browser testing.
If I have an AngularJS directive -> say a button that has a spinner -> and
it appears multiple times on a page, how can I make sure to click on that
particular button...when it has no DOM ID or unique class? In my case,
"Login" and "Some Other Button" are dynamic and would be unique for all
buttons in the ng-view.
<my-requesting-button text="Login" class="ng-isolate-scope ng-scope">
<button type="submit" class="btn btn-large">
<img src="/img/progress.gif" style="display: none;">
<span>Login</span>
</button>
</requesting-button>
<my-requesting-button text="Some Other Button" class="ng-isolate-scope
ng-scope">
<button type="submit" class="btn btn-large">
<img src="/img/progress.gif" style="display: none;">
<span>Some Other Button</span>
</button>
</requesting-button>
Soda (basically directly from the example):
browser
.chain
.session()
.open('/')
.clickAndWait('...LOGIN BUTTON REF?')
.waitForPageToLoad(2 * 1000)
.clickAndWait('...SOMEOTHER BUTTON REF?')
.waitForPageToLoad(2 * 1000)