There are plenty of effects for wingtips using the some of the default FS9 effects and textures. I have placed many of these on some of my favorite downloaded acft.
Problem is, I have to hit the I key to start them up. So having wingtip vapor vortices is not the problem, it's how they are generated. I think this is what JIMBO is asking.
There are a couple of XML gauges out there that do with "timing" of effects. One displays the sonic boom/vapor effect and the other displayed the engine exhaust based on the N1 factor. Both of these are "timing" XMLs and I have used them to generate other effects for my acft.
What we need is an XML gauge designed specifically with the correct timing parameters. jknight's solution sounds good, the AOA. But you may be at a fairly high altitude and flying slowly and your AOA could be increased, which would activate the vapor vortices.
I think maybe AOA plus altitude would be the two parameters required in order to display the effects correctly and at the right time that JIMBO is looking for.
OK, so who is going to learn XML gauge language?

Systemax Sabre Ultimate gaming rig.
I got all the goodies and all the power I need to run anything thrown at me for the next two months!