Filter posts by multiple taxonomies and multiple terms for each one

I’m implementing a little post filter for one of my categories that displays a custom post type of “Organisation”. There are two taxonomies this post type uses: Country and Discipline. Country is a “global” site wide taxonomy used by other posts but discipline is specific to “Organisation”.

Now, my custom query works fine with:
&taxonomy=discipline&term=my_discipline_term
OR
&taxonomy=country&term=my_country_term

however the query arguments do not allow something like in__taxonomy and in__term. Each taxonomy would need to be associated with the terms to filter it by, kind of like:

in_taxonomy_term= array(‘country’=>’country1, country2…’, ‘discipline’=>’discipline1, discipline2…’)

This would allow filtering by multiple taxonomies and multiple terms within each.

So, since this isn’t supported by WP yet, my question is what’s the best way to achieve this functionality?

I’d write my own SQL to achieve this.