Turkish percussion notation and changing stem direction for always

[Adam Good]

Hi Everyone,
I'm working on some Turkish usul percussion notation and the standard is,
rather oddly, to have the low pitched "dum" sound on the top line and
highest pitch "tek" sound on the low. See the snippet below.

Problem that I can't solve: stem direction needs to be the reverse of what
it is showing. Top line needs to point up, bottom line needs to point down.
Without adding \stemUp or \stemDown , could anyone help me and my lack of
coding skills?

btw have a look at a couple simple rhythms in turkish music here:
https://compmusic.upf.edu/examples-usul-mmt

Thank you very much in advance.
Adam

%%%%
drumPitchNames =
#'((dum . kdl)
(tek . kdh)
)

#(for-each
(lambda (k-v)
(module-define! (current-module)
(car k-v)
(alist->hash-table (cdr k-v)))
)
'((kudum-style .
((kdl () #f 5)
(kdh () #f -5)
))
))

nam = \lyricmode { dum4 tek tek dum }
mus = \drummode { dum4 tek tek dum }

<<
\new DrumStaff \with {
\remove "Bar_engraver"
drumStyleTable = #kudum-style
\override StaffSymbol #'line-positions = #'(5 -5)
\remove "Time_signature_engraver"
\autoBeamOff
}
\mus
\new Lyrics {
\override LyricText.font-family = #'typewriter
\nam
}