The spec's say this is for a 10 speed, can...
The spec's say this is for a 10 speed, can you use it for a 9-speed setup?
No, DynaSys 10 speed for Shimano uses a different pull ratio and is not cross compatible with 9 speed systems.
That being said, I have heard of some riders posting on forums about them adding spacers to the 10 speed rear derailleur cable clamp to work with 9 speed shifters. I haven't tried it however.