According to Abit site, ZM6 supports FC-PGA Celerons although their FAQ page says that it does not support cC0 stepping FC-PGA Celerons due to some hardware problem.
Celeron 700 comes in both CB0 and CC0 steppings. CB0 (Retai: SL4E6, OEM: SL48F) and CC0(Retail: SL4P2, OEM:SL4P8) so check with your CPU stepping.
On the other hand, I take that the reason that cC0 is not supported is because of a small voltage spec difference, and I have a feeling that cC0 works fine. But don't blame me on this if it does not.