Possible to change the three-quarters-flat symbol?

[Alexander Ness]

Hello,

I am a composition student in New York. I recently discovered
LilyPond, and am excited by its flexibility, clarity of design, and
high output quality.

Is there a way to change the three-quarters-flat symbol, and---more
generally---to designate  symbols for other microtonal accidentals
(arrows for 1/8 tones, for example)? The current 3/4-flat symbol looks
confusingly like a double-flat; far more common, at least in the U.S.,
is a symbol combining the 1/2- and 1/4-flats by fusing their stems, to
create a symmetrical heart shape with a vertical line extending
upwards.

Thank you for your help!

Alexander Ness