Hi,
I think that the latest version of PUN is now offering a built in system for synchronizing Mecanim, so you should use this instead of trying to do it yourself.
If however you want to do it yourself, basically, you don't synch Mecanim, you synch only the exposed values you use in PlayMaker to control Mecanim, so if you have a float that controls Mecanim, this float is what you need to synch, just like in the demo, the animation state is synched using an int, you can use the same technic for Mecanim.
Bye,
Jean