I think I got mine to work yesterday using:
Set bond0 ; ports/slaves = eth0 eth1 , IP xx.xx.xx.100 Subnet mask xx.xx.xx.0 gateway xx.xx.xx.1
Set vmbr0; ports/slaves = bond0 , IP <same as above(bond0)> subnet <same as above (bond0)> , leave gateway address null.
I don't know why vmbr0 needs an IP? But it seems like it does or it wont work. If someone knows that would be great to know why? And if this looks right. Its easy once you knwo what to do but seems impossible when learning.. thanks to sgtfoo for pointing me in right direction.