You can do minor adjustments at the handle. But otherwise there is a hole back of the wheel hub at the bottom with a rubber thingy in it. Remove the rubber thingy and you can probably get a screwdriver or something in there to spin the adjuster.
I've never actually done it that way, but it can be done. I usually remove the calipers and brackets, pull the rotors, and adjust the thing that way. It's easier to see how much you are moving it and to make sure you're going the right way. Plus it's only 2 bolts, and you can check on the pads.
Question: Will e-brake shoes auto adjust if you pull it in reverse? kinda like ones on cars with only drums in the bake? That would be super easy!!