Hi,
The Synclavier V does not allow to import your own samples in the time slice engine, you are right.
We've considered the option of integrating this feature in the software.
But we've chosen to focus on the FM and Additive engines which already offer a crazy wide range of sound design possibilities, especially combined with the time slice feature.
This said, if that's really what the Synclavier V users want, we may reconsider including the resynthesis engine in a v 2.0.
At least give it a try now if you are interested by this synth, you might be surprised.