Let me mention first that, just so you know, you're not the first person that has tried to get around the lack of VSTi support in SVP.
That said, sending MIDI out from SVP over IAC is easy:
Name an IAC "channel" if there isn't already one.
Create an Instrument in SVP with the output instrument set to that IAC channel.
Now the fun part.
Figure out how to get Cubase to receive input from the IAC bus. (Can't help you there - I don't use Cubase)
Last issue and definitely an important one: To make this work, only one app at a time (so, gotta be Cubase) can use the ASIO. SVP has to be used as a MIDI-only app. You cannot have your interface's ASIO driver in SVP's ASIO folder. (You can put Sound Manager in there if you need to "hear" something from SVP directly.
Good luck. I've never tried this but I'm pretty sure I would have heard about it if it worked. I suspect that Cubase will only send on IAC and not receive.
But if it works, by all means, please tell everybody!