how to change upstream route, preserving subroutes in ember?

Say you have a router like so:

@resource 'products', ->
  @resource 'product', { path: /product/:product_id } ->
    @route 'description'

and you're currently in the

http://ift.tt/19xYOwL URL.

From this location, if you click a link to a different product, how do you modify that link so that the resulting page is not

root.com/products/37

but rather

http://ift.tt/1I13JVv?

I want to preserve the subroutes, as you can see. Or is there a better way to do this, for example, using an application controller property that gets passed around to every descendant route/controller?