This can already be done, I'm not gonna say it's easy but there are several ways of doing this.
#1 you can save a sample onto a cd and use something like a cdj to do the scratch effect and later alter it further in reason, OR
load it into nnxt and hook up matrix to it, cv it so that the amount on each matrix note would act as an amount of the sample getting "scratched", don't forget the FW and BW modes on the nnxt control panel.
Kurt wrote out a healthy "little" 3 page example in his power book how this can be done
