You don't need to talk to anyone. Simply fill out a
Letter of Permission before you register for the course. Once approved, go register for the summer session of the course at the other University. Summer school registration deadlines are different for each University, so take note of that.
I am currently taking Bio235 at Athabasca University to fullfill my Bio 2A03 credit. Just to give you an idea of what to expect, I filled out my Letter of Permission in June, got approved a week later, and then registered for the online course to start in July.