Tokens for taxonomy aliases

I would need to have in admin/config/search/path/patterns -> Content Paths, a token that points to a given taxonomy url alias, not just its name, because they differ a lot, but all I can find is a reference to the term name I've assigned to my content. Is there a way to accomplish this?
I thought to create a field in article content type, formatted with php code, but I find it difficult to access tokens and tokens api from there.
Hope I've been clear enough.
Any help would be appreciated!
Thanks