We are planning on implementing 4/10's with my company. I understand the process of the voting and getting the employees on bored. But I am not clear on the over time compensation. Because California law cleary state over 8 hours in a day is considered over time. is an alternative work schedule a clause? So, for example anything after the 10th hour is considered over time as well as a 5th day of work?

I'm no expert on CA employment law (shudder) and thank you know who I don't have to put up with CA emp laws. But based on my inexpert knowledge of having read them, it is my understanding that if the ee's vote for an alternative work schedule, that alters the overtime provisions normally built into a regular 8X5 work week schedule. Thus, if ees do vote in a 10x4 work week, then OT would not kick in unless they work a fifth day or more than ten hours in their scheduled four days. I don't recall the exact wording, but I do recall there being some rather strict regulations on how the vote is to be conducted.

Here you go.
http://www.dir.ca.gov/iwc/52600hearingnotice.html