Well, I think you should be using the 4 pole analogue filter, because it's the closest there is to the Moog's 24db ladder filter on the Virus. I don't know if you're after the self oscillating sound by itself or combining it some other source. Either way, you can probably find some sweet spots for it and modulate only on that range: filter cutoff and resonance at the same time, with some soft knob locked to the range and settings you know that sound pleasant. But to be honest, you may want to put another low pass filter in series with cutoff link turned on, just to blend the harshness (digital kind) from the tops a bit, or use the EQ for the same purpose. I think you can get very close, but with a lot more work. I sometimes find that even adding effects like chorus with no movement on it can help make it sound more warm and "analogue" in some situations - even when going for a dry sound of another machine. Don't know... But my programming advice when dealing with more then one parameter is finding the sweet spots on the extremes and then placing the knobs there and placing the amounts so that it can only go from one sweet spot to the next - in between it usually sounds good to.
But if you're looking for that sound and you're able to use software, if you don't have such a wild beast like Monark or Diva - probably the best and fastest way to get there, try this one 'cause it's free:
http://kunz.corrupt.ch/products/tal-noisemaker
and don't underestimate that one! it sounds better then most stuff you have to pay for! And I've done some experiments with self oscillating filter being modulated by an LFO myself with that, I'll show you the raw example:
https://dl.dropboxusercontent.com/u/...4/talcoiso.mp3
sorry for the ear piercing highs on this, but that's what I was testing atm. Cheers