JAR requirement states you need a 100hrs PIC to begin CPL
You sure? I think it means you must have 100 hours PIC before licence issue, not course commencement.
I don't know about FAA but in during a JAA CPL training course, all time is logged as Pu/t since you are undergoing training. FAA rules do seem to allow safety pilot time to be logged (whereas JAA doesn't) but actual training courses (whether FAA or JAA) must surely be dual!
Cheers
Whirls