In this answer to a question I asked a while ago, he said it's possible to have a script executed every boot.
I created a file (without extension) that contains the following:
#!/system/bin/sh busybox mount -o bind /emmc/Android/data/com.google.android.music/ /sdcard/Android/data/com.google.android.music/
I made sure the target folder exists and saved the file to
/system/etc/init.d, but in fact it looks like the script isn't executed.
P.S. the script file's properties are: