Softimage Xsi: particle deformation and motion vectors

hi all. im currently running into an annoying problem when deforming a particle stream along a curve: the velocity vectors tangency is not maintained, therefore no proper motion blur can be computed ( blur along the deformer, of course). please give advise on any possible workarounds to fix that issue. what ive tried so far is animating the emitter along that curve, leaving the particle speed at zero in order for the particles to stay on the deforming curve. the problem with this solution in conjunction with some inheritance applied, the particles are just being spread, thus leading the particles to leave the deformer. im fully aware of why thats the case, so here another question: is it possible to drive the inheritance by the motion of the emitter, in the case it may help? thank you in advance!