A local tailor should be able to hem it. I know Barb's talked about hemming her band's 16oz kilts. If I were doing it, I would probably clean finish the edge (either serge or zigzag) then turn up the hem just once and stitch by hand, not machine.

Don't forget to have them take a slightly deeper hem in the underapron and other places where the kiliting selvage would ordinarily be turned up just a touch to keep the lower edges from showing.

You'll probably need to baste and re-set the bottoms of the pleats with steam and (Lots of) pressure because that inch or so that is turned up will now have the 'crease' going in the opposite direction (ins become outs and vice versa). Lucky, wool doesn't mind that (with a little steam encouragement). I would do it myself instead of asking the tailor to do it because they will need the pleats open to hem, and you need them basted to press. And most tailors (at least the ones around here) have no idea what to do with a kilt.

To bad you aren't local to me, or I'd offer to do it for you.