How Do Erg langs handle causative?

Markus Miekk-oja undrade:


> This got me interested. How does a 'truly ergative' lang handle causative
> transitive constructions of the kind "I made him buy it" according to them?
> (For surely, they must be able to handle them in some way).
This question has been hanging unanswered in the air for nearly
a week now. Anyone out there with a good answer to it?

Daniel