when you send a message to trigger a new slice, do the following:

1) send a [vline~] ramp to cut the volume

ie,

[tabread4~]
|
|      [0 5. 0 5 5(
|      |
|      [vline~]
|      |
[*~ ]


2) delay your slice message 5 ms so that the new slice is retriggered exactly when the volume is zero.