You can’t do it via the Key Commands page of Preferences, I’m afraid, but you could do it by hand-editing the keycommands_en.json (or whatever language version is appropriate for your own system) file in a text editor. Editing JSON files in a text editor is a slightly problematic thing because it’s very easy to make a syntax error, but if you’re careful all will be well. Take a look at the excerpt below:
{
"common" : {
"contexts" : [
{
"context" : "kStepTimeInput",
"shortcuts" : [
{
"NoteInput.Pitch?Pitch=C" : [ "A" ]
},
{
"NoteInput.Pitch?Pitch=C&Type=kSharp" : [ "W" ]
},
{
"NoteInput.Pitch?Pitch=D" : [ "S" ]
},
{
"NoteInput.Pitch?Pitch=E&Type=kFlat" : [ "E" ]
},
{
"NoteInput.Pitch?Pitch=E" : [ "D" ]
},
{
"NoteInput.Pitch?Pitch=F" : [ "F" ]
},
{
"NoteInput.Pitch?Pitch=F&Type=kSharp" : [ "T" ]
},
{
"NoteInput.Pitch?Pitch=G" : [ "G" ]
},
{
"NoteInput.Pitch?Pitch=A&Type=kFlat" : [ "Y" ]
},
{
"NoteInput.Pitch?Pitch=A" : [ "H" ]
},
{
"NoteInput.Pitch?Pitch=B&Type=kFlat" : [ "U" ]
},
{
"NoteInput.Pitch?Pitch=B" : [ "J" ]
},
]
}
]
},
"delta" : "true",
"version" : "1.2.0"
}