Share OpenVPN Connection from OSX to Linux?

Hello,

I've downloaded the eval version of parallels today and it's looking awesome so far.
There's one problem, though:

I'm using OpenVPN to connect via Airport to our gateway.
The gateway is the OpenVPN server, my MacBook is the client.

This all works fine (using the tunnelblick client for OSX) but now I'm wondering how
can I access this existing VPN connection from inside the VM (which runs gentoo linux)?

I tried various combinations of Bridged- and Host-Only settings but to no avail.

In Host-Mode I can share either the wired (en0) or airport interface to the VM but what
I really want is to share tun0. That one doesn't show up in the "Share"-Dialog in
OSX, though...

So, as of now, I could probably bridge the Airport device and run two instances
of OpenVPN, one in OSX and one in Linux, over it but that seems backwards.

Is there a way to access the tun0 device in linux so I can *share* the existing
VPN connection instead of duplicating it?


Any hints would be highly appreciated