How to get a custom type from ExecutionEngine::runFunction

I'm starting to work with custom types and wondering how I can
pass/return them via the ExecutionEngine? runFunction returns only a
GenericValue, so it appears somehow I must make use of its pointer member.

For example, how do call this function/type:

%struct.mine = type { i32, i8, float, double }

define void @make_struct(%struct.mine* noalias sret %agg.result, i32 %a,
i8 signext %b)