refind.conf for multi-boot on Macbook Pro

refind.conf

# /EFI/refind/refind.conf

# gives you chance to change choice, manually
timeout 5

# tools for debuging, reboot without pushing damn button
showtools shell,reboot,exit

# scan internal disks, extenal(USB?) disks, 
# optical drivers, and specify by following
scanfor internal,external,optical,manual

# gives refind a chance to wait for device being ready
scan_delay 5

# useful when all your kernels is located on default 
# device, you may have no need to write further 
# menuentry configs
scan_all_linux_kernels

# default boot item, title or index to menuentries
default_selection "Gentoo Linux"

# custom menu entry 
# in my case, I've installed Gentoo with EFI boot manager
# there's a efi file located on 'efi-boot' partition.
# So I'm just "chaining" rEFInd with GRUB bootloader. 
menuentry "Gentoo Linux" {
    volume "efi-boot"  # if your boot partition isn't default

    # you may check this location by just hitting Esc on startup screen
    loader EFI\gentoo\grubx64.efi 
}

Chaining bootloader is easy, so I could make any change just to GRUB, and no need to make any further editing with rEFInd. (such as adding new kernel, appending kernel params like UUID= stuff.)