On all (free) X implementations out there (the only exception
I know is older X11 on IRIX), mouse wheel events are usually
mapped as normal button press and button release
events:
# Extract from the X configuration file
Section "InputDevice"
[...]
Option "ZAxisMapping" "4 5"
[...]
EndSection
As you see, up is button 4, down is button 5: adesklets does
report those events as usual. You can check how they are
mapped on your system using the
xev utility -- but I do not know anyone
who does map the wheel differently: too many applications
hard-code those values these days to make them worth
changing. Yours,