I was bored, and I was playing around with sfz anyway, so here's an example of using volume and panning with VST instruments:
(link removed)
Note that you need the sfz VSTi, the Kjaerhus Classic VST series would also be nice to have. sfz requires soundfonts, I've been using ConcertGM0.97test3.sf2 for the first sfz instance and SGM-180 v1.5.sf2 for the other instances, so those soundfonts would be preferred. I guess it sounds ok with other soundfonts, too.
I use the first macro (SF0) to control panning here, hence there is no SFx command.