attaching buzz marking in percussion

[M@ Nichols]

Instead of putting a single, double, or triple slash tremolo on a snare drum note, how do you add the "z" as a roll?
\version "2.12.2"
\drums {
  sn4 sn8 sn sn4 sn4:32
  sn8 sn16 sn sn sn8 sn16 sn8 sn sn4
}

How would I add the "z" marking to the red snare example?
-- 
Matthew R. Nichols

  "Therefore do not worry about tomorrow, for tomorrow will worry about itself.  Each day has enough trouble of its own" --Matthew 6:34

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