it is not possible with software like r8brain or the like. nebula has its own fileformat, for the vectorfiles. there is a way to do it in NAT (the sampler), but it was buggy, so i did not touch it anymore.
i don't know if it works better now. you have to ask giancarlo. but it was not very high on the priority list back then. the realtime-conversion in nebula works pretty well.
system 1: windows 8 32 bit - samplitude prox, tracktion6, reaper system 2: mac osx yosemite - reaper(32+64bit), tracktion6(32+64bit)
both systems on: macbook pro (late 2009), core 2 duo 3,06 ghz, 4 gb ram, graphic: nvidia geforce 9600M GT 512 MB