It is indeed the ARP Odyssey (using ring mod, which on the odyssey is a XOR logic function on the square oscillator outputs, I believe) + Distortion effect (MXR maybe) + flanger + speaker cab. All these stages (besides the XOR ring mod) are available on the virus and I have got really close to the sound (with a couple of cheats, too), so I think the only real way to get it just right is a hell of a lot more tweaking, or relying on access to put in emulations of the SPECIFIC things that Billy Currie used... Despite the many toys that Access regularly gives us, I'm not going to hold my breath for something so specific.... although a XOR ring mod would be nice...
I'd die for a Billy Currie / Ultravox sound set but i have come to the conclusion that it might be easier just to buy the MKII Odyssey 