I couldn't find any information on C. brevifolia in any of my reference books but C. atlantica, libani and deodara are listed. Plant Propagation by Hartmann & Kester sums them all up:
C. atlantica and C. libani are difficult to root. C. deodara can be rooted by wounding cuttings and using bottom heat: cuttings are collected in late fall to early winter and quick-dipped with 5,000 ppm IBA.
I hope you can find something more.
