How it works? Hard to explain :)
On Legacy BIOS it works same as Chimera.
On UEFI BIOS it use some kind of rEFIt and DUET bootloader fork. It can patch kexts on the fly before boot, so you don't need to make real changes to kexts, like AppleHDA for sound, or IOAHCIFamily.kext for TRIM.
Clover...