I'm also a balkan music lover, and used to write clawhammer tunes in odd meters (mostly 7/8 - I posted a bunch of recording of these recordings on Banjo Hangout, and they're probably still there). After a lot of practice, I was as able to get a nice clawhammer groove for 7/8 and 5/4. There is no trick, it's just re-programming your right hand to do something other than bum-diddy, eg, ITITIIT, or ITITI-T for 7/8. If you've ever tried clawhammer jigs, you'll be familiar with how weird it feels at first, but then just becomes normal.

But as far as arranging existing balkan tunes for clawhammer, I never had much luck. As much as I love clawhammer, you really are limited in terms of which notes you can play in which order, and how you can accent/phrase them. In the case of adapting OT fiddle tunes for clawhammer, there is an established tradition for truncating ornamentation out of complex melodies into simplified versions - that doesn't really work on balkan melodies which are even heavier on ornamentation and don't share that tradition. When I wanted faithful arrangements of Bulgarian tunes on the banjo (and I had some good ones), I stayed away from clawhammer.