I have built a vmware lab environment entirely with vmware workstation 9.0, this post document the process on enabling fault tolerance (FT) in nested VM. The nested VM was created with vcenter which is another vm created by vmware workstation.
Limitation of fault tolerance
1. The VM has to remove CD/DVD, because CD/DVD is not supported by FT.
2. The VM has to remove USB and sound devices because FT is not compatible with these.
For a full list of incompatibilities use google to look for this document vsp_41_availability.pdf, the above 2 points should be removed from your VM that requires FT enabled.
Extra parameters for nested vm
You need to set three parameters before enabling FT:
replay.supported = true
replay.allowBTOnly = true
replay.allowFT = true
These parameters were not available on your VM settings, you need to add them yourself.
After you have created a VM and installed the OS, shutdown the VM and right click the VM.
Enable fault tolerance on vm
You need to enable the vm that you want to protect with FT.
At any one time only one VM is active, the secondary VM will get the same state as the primary VM, the VM on the esx2 host will remain as secondary until esx1 host fails.