Potresti  assegnare una scorciatoia a uno script  come questo: 
set text item delimiters to ":"
display dialog "" default answer ""
set ti to text items of text returned of result
if number of ti is 1 then
    item 1 of ti
else if number of ti is 2 then
    60 * (item 1 of ti) + (item 2 of ti)
else if number of ti is 3 then
    3600 * (item 1 of ti) + 60 * (item 2 of ti) + (item 3 of ti)
end if
tell application "iTunes" to set player position to result
 O installa ffmpeg con   brew install ffmpeg --with-afplay    e usa un comando come   ffplay -ss 1:23:45 file.mp3   . 
 Uso anche script come questo per cambiare la posizione di riproduzione con la tastiera: 
try
    tell application "iTunes"
        if player position < 15 then
            previous track
        else
            set player position to player position - 15
        end if
    end tell
end try
try
    tell application "iTunes"
        set player position to player position + 15
    end tell
end try