Just get hold of Noteworthy, copy the music out, and let it automatically transpose for you. We used that approach for the New Mills klez sessions.

Lynne, most of the difficulty of clarinet playing is in the crossover between the registers- it's not an octave, it's a twelfth, so the fingerings for the high notes are different from the low notes. get that bit right, and you've made it (apart from reed control of course!).