Your BIOS must have the option UEFI Boot and it must be enabled in order to install operating systems in UEFI mode.
Notice that when this option is enabled, it shows UEFI before the drive name.
OS X installation
You can make an installer or download one from my signature. You don't have to boot the OS X installer in UEFI mode, it's only needed in the following step, to install Clover.
IMPORTANT: to install Windows 7/8 in UEFI mode, the partition table must be pure GPT, it can't be hybrid MBR like used in old BIOS mode, so when you create the partitions in Disk Utility, do NOT change the Windows partition to MS-DOS (FAT), keep all partitions as Mac OS Extended (Journaled), you will change the other partition(s) format later.
Install OS X in the first partition.
If you have Windows pre-installed do not format the EFI partition (newfs_msdos), just mount it (mount_msdos).
If you used the raw image, you can just copy Clover from the pen drive to the HD
Format a pen drive as FAT32 and install Clover in it.
You need at least the drivers FSInject, OsxFatBinaryDrv and VboxHfs (or ) in the folder /EFI/CLOVER/drivers64UEFI (installed by default). Depending on BIOS you may need OsxLowMemFix (Insyde H2O), EmuVariableUefi (Phoenix UEFI) or OsxAptioFixDrv (all other).
Do not select the option "install for UEFI motherboards", it only works if the pen drive is partitioned in GUID. After installing, create the folder EFI/BOOT in the pen drive and copy the file EFI/CLOVER/CLOVERX64.efi to EFI/BOOT/BOOTX64.efi
Start the system using the pen drive to test UEFI boot.
Run the following commands in terminal, replacing X by the HD number.
To format the EFI partition as FAT32 To mount the EFI partition Create the folder EFI in the EFI partition.
Copy the folder EFI/CLOVER from pen drive to the folder EFI in EFI partition.
Boot from the pen drive again. In Clover menu, go to Clover Boot Options of SATA drive (usually 0x1F, 0x2) and select Add as UEFI boot option. Now you will be able to boot Clover from EFI partition without the pen drive, in UEFI mode.
I recommend reading this topic for more information
To make an UEFI installer in USB, open Command Prompt as administrator and run the commands Copy all files from the image (DVD) to the pen drive.
For Windows 7 you need to copy the folder efi\microsoft\boot to efi\boot (one level up), copy the file bootmgfw.efi to that folder and rename it to bootx64.efi
The file bootmgfw.efi is in the folder \1\Windows\Boot\EFI\ inside the file \sources\install.wim from DVD. Open install.wim with .
For Windows 8 the usual steps are enough, but it can't be an "AIO" (all in one) image, x86 and x64 (with efi\boot\bootia32.efi), it must be x64 only (with efi\boot\bootx64.efi).
Before installing Windows you need to change the partition format to NTFS. You can use gParted from a Linux live CD.
IMPORTANT: Windows installer formats and renumbers all partitions after the destination one, because it creates a reserved partition, so if you will install Linux, do it after installing Windows, or install Windows in the last partition.
If you use loader to activate Windows 7, you can inject SLIC table using Clover instead.
Download SLIC 2.1 binary and certificate
Rename the file NAME.BIN to SLIC.aml and put it in the folder EFI/CLOVER/ACPI/WINDOWS
Put the certificate in C:\ and run in Command Prompt (as administrator)
slmgr -ilc C:\NAME.xrm-ms
slmgr -ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
The only important detail is to install GRUB legacy in the Linux partition and not in MBR (for example, select /dev/sda5 and never /dev/sda).
The file grubx64.efi is installed in EFI/"distro name" in the EFI partition.