I'm not sure I understand what you mean by additional mapping.
Here's all that's needed in the template:
<div class="city"><span class="name"></span> has <span class="population"></span> residents</div>
And the mapping would be: [ 'city': [ '.city', { name: '.name', population: '.population' } ] ]
If you don't want to manually define a mapping, you could do it automatically by assuming that some attribute like `data-bind` corresponds to a binding, but Simulacra.js doesn't make assumptions like that.