AFAIK, the easiest way to do this is to use my rEFInd boot manager, which enables switching between EFI-mode and BIOS-mode booting. You'll need to uncomment the
scanfor option in
refind.conf and ensure that
hdbios is among the options. Also, be sure to use the latest version; pre-0.8.0 versions had weak BIOS-mode support on PCs, and I made some improvements in 0.8.1 (the latest as I write) that are worth having.
That said, many BIOS-only OSes won't boot from a GPT disk, which means you'll need at least two physical hard disks to do the job. You should be able to do it with one disk if your BIOS-mode OSes all support GPT, though. (Linux and FreeBSD both do, for instance.)
Also, I don't see much point to booting Linux in BIOS mode if you're dual-booting with an EFI-mode OS unless you have specific problems with EFI-mode booting. (Proprietary video drivers sometimes have problems in EFI mode, for instance.) You'll boot more quickly in EFI mode, and you'll have more choices in boot loaders and boot managers. If you use rEFInd to select the boot mode, booting in EFI mode means you can eliminate GRUB and all its flakiness. (I'm not a fan of GRUB.)
Converting Windows from EFI-mode to BIOS-mode booting is another possibility, but I know of no site that documents the process. It would be the opposite of the procedure described on this page, though -- that page describes how to convert from MBR/BIOS-mode booting to GPT/EFI-mode booting.