Problem with openvz creation via API

Hi,

I'm trying to create an openvz container via API.. seems to be working fine, but there's one option that seems to be missing.
We use nfs inside the container, so we need to add FEATURES="nfs:on" to the conf file.
Is there a way to do this via API? I couldn't find the 'FEATURES' option in the API docs.
Also, if I try creating the CT adding -features=nfs:on, I get:
Unknown option: features

Any ideas?
Thanks