Using a score rooting technique similar to what others have discussed, I successfully rooted Marseille Black VS in 14 days. I only have two cuttings, and do not have a control group, but it sugests that score rooting helps with at least this reputedly hard to root variety.
Both cuttings have roots showing through the cup and are starting to leaf out.

Method:
Cuttings stored in the fridge for 2 weeks after receiving them
Wash cutting
Score with grafting knife
Dip in 7X Dip'N Grow
Stick in 50% Perlite, 30% Peat, 20% fine vermiculite
Propagation box @ 85-95F, 24hr/day grow light