True approaches

How does the 540 handle approaches based on true headings (i.e. in northern Canada, where magnetic variation is large).  Does the desired track and actual track and course display simply revert to True (and presumably annotate that the displayed headings are True?) If so, what about en route in that environment... are headings true or mag?

Thanks... that helps! So to fly an approach using true headings, I'd simply change the bearing reference, and all would look normal. (Presumably if one didn't change the bearing reference, one could still fly the approach, but it would look like a large crosswind, with the mag heading well off from the true track).