The answer is YES. My mid 2007 iMac is currently configured in such a fashion. My Windows 8.1 uses a BIOS boot. I have two NTFS partitions, one exFAT partition and two HFS+ partitions. (I also have the hidden EFI partition and the hidden OS X recovery partition) The exFAT partition is read/writeable from all operating systems.
Do you need to keep your current Windows and/or OS X operating system partitions? Or, will you be starting from scratch and erasing everything? If you need to preserve your existing windows system then I would recommend using WinClone (cost $30) to move the operating system (preferably) off computer to external storage temporarily. OS X can be backed up and move off computer using the disk utility.
To complete the install, you will probably need to boot from a flash drive containing a copy of the hidden recovery partition. Do you still have your hidden internal recovery partition and does it work? (Better yet if you have already made a flash drive copy) If you don't know the answer, then reboot your computer, then hold down the alt/option key and see if the recovery partition appears.
I assume you have installed windows 7 on the mac before. If not, then do you know if you get "Select CD-ROM Boot Type:” error during Windows install described here? If you do, then you will need to make a new install DVD.
To get things to work, the idea is to do everything opposite of what apple tell you to do. I would recommend the following steps (assuming the internal disk can be erased and you are saving nothing.)
- Boot from the flash drive.
- Create a new GPT partitioned disk using the Disk Utility. The first partition will be for Windows 7, so format it "MS-DOS (FAT)". The second partition will be ExFAT formatted. The third and fourth partitions will be for OS X so choose "Mac OS Extended (Journaled)".
- Exit the Disk Utility and select install OS X from the internet.
Boot to the installed OS X. Open a Terminal window and enter the command:
sudo bless --device /dev/disk0s2 --setBoot --legacy
Insert the Windows 7 DVD and reboot the computer. Hold down the alt/option key and select the DVD to boot from. Hit the space bar when prompted to continue booting from the DVD. (You only do this once.)
- Install Windows 7. Make sure you install to the correct partition and format the partition NTFS.
- Install bootcamp drivers stored on a MBR partitioned, FAT formatted flash drive. The drivers can be downloaded under OS X from here. I suppose the drivers could also be copied to and installed from the exFAT partition.
- Enjoy hours of installing hundreds and hundreds of updates.
Of course, I have left out many details, but most of the time no one responds. After I while, I learn not to spend to much time on an answer, unless someone shows interest.
I no longer use ExFat formatted internal partitions. I found ExFat to be unreliable. I now use MS-DOS(Fat).