Not possible...well not on 11gR2 anyway where I double checked...you can only copy files.
Enables you to copy files between Oracle ASM disk
groups on local instances to and from remote instances.
You can use the cp command to:
Copy files from a disk group to the operating system
Copy files from a disk group to a disk group
Copy files from the an OS File system to a disk group
I think this might be for 11.1, I've only got ASM on 11.2 so can't confirm but would be good to know if that is the case.
cp command allows you to copy only files.
Hope Oracle will add directory copy in feature releases.