Ok, let's do this:
Using the Default template (because it will be easy to work with) do the following in this order:
1. from the Window Menu, select ScoreManager
2. Under the Sound column click Edit Player, Kontakt should open, load in any SnareLine Manual Lite (I'm suggesting Lite because it will load faster for this tutorial), once it is loaded you may close the Kontakt window
3.Under the Percussion MIDI Map column, click the file name that is presently listed, this opens up the list available Percussion MIDI Maps (the XML files), scroll to FIN12_VDL255 Battery and select SnareLine Manual
4.In the lower right corner where it says Notation Style: Percussion, click the Settings button, if you are familiar with Finale pre-2012 this information was found in Staff Attributes, everything has been consolidated into the ScoreManager
5.Once you have clicked the Settings button, the Percussion Layout Selection window appears, in this window select VDL2.5 SnareLine Manual Full/Lite (MW)
6. To verify that everything is correct, click the Edit button after selecting your layout, you should see all of the sound names, staff placements, and notehead assignments.
7. At this point, click OK to close the Percussion Layout Designer box, click Select to close the Percussion Layout Selection box, and close the ScoreManager Window
The key to all of this to do Percussion MIDI Map then Percussion Layout. If you forget and do the steps in reverse, just do them again in the correct order. It's also important to know that prior to Finale 2010, playback and layout were separate items. Beginning with 2010 they have become linked, one affects the other. With 2012, changes to both may now be made in the same window, the ScoreManager.
I think this covers everything. Let me know how things develop.