You mean automatically, without requiring that your user turn it on and off with CFwdAll?  Yes.  This is from someone who wanted calls to go to VM, but you can just create a Translation Pattern instead of a Route Point in the Afterhours_PT if you want to ring a different extension.

Create one or more Time Periods that coresponds to the times that you want the calls forwarded to VM.

Create a Time Schedule that includes all of the Time Periods you just created.

Create a new partition, Afterhours-PT (or whatever you like).  Assign it the Time Schedule you just created.

(These three are all done from the Call Routing | Class of Control menu)

Create one Route Point for each DN that you want forwarded to VM.  For each...

          Assign Line 1 to the same number as the DN you want forwarded, but in the Afterhours-PT.

          Assign the Voice Mail Profile

          Check the Voice Mail box next to Call Forward All

Edit your Calling Search Space.  If you have multiple, either edit them all, or just the one(s) that apply to your incoming calls (i.e. assigned to your voice gateway(s)).  Insert the Afterhours-PT and move it up the list so that it is first.