brendan
i don't have virtual interfaces (or VIPs, Virtual IPs) on my device, but i do have a 2 link bond created, and have VLANs trunked across that bond and OpenVPN runs on one of the VLAN interfaces.
for instance: interface p1p1 and p1p3 are bonded to create the interface bond0. i trunk VLAN 50 and VLAN 52 across bond0, creating interfaces bond0.50 and bond0.52. each of those interfaces have their own IPs. 192.168.50.1 and 192.168.52.1, respectively.
i bridge the bond0.50 and tap0 interfaces together using a script called by the config file, and have the vpn process use the tap0 interface on the bridge.
given my setup, i would think you can run on a virtual interface or VIP. you might need to hack away at it until you get it working.
