If you have a polycarbonate MacBook, remove the HD, install Haiku on it from a compatible PC (or through a USB to SATA, etc. through a VM) to normally install Haiku. Put the disk back in the Mac and restart. Wait for Haiku to be detected (the ? will flash for a minute) and at least from all my adventures with Haiku on the Mac, this seemed to work with the Nightlies (not sure if it does now).