I downloaded the Mavericks DMG and exported it to the USB flash drive using ROSA Image Writer (win32diskimage dind't work for me). So far so good. Restarted, booted from USB, entered the amd64 -v boot flag and it boots, everything loads up untill the message "AppleNForceSerialATA: found 0 entries" appears, followed by the still waiting for root device message. Restarted and booted to Windows. Did the fix Niresh suggested with the BootDiskUtility. Formated my other flash drive, deleted boot, replaced with the fixed one, renamed it to boot, went to Extra > Library > Extensions (I think thats the path) and replaced the kernels. Booted from this flash drive, everything fine. A "press any key to continue" prompt appears. However, if I press a key, it just reboots my computer, no matter what bootflags I use.
Any further help is appreciated.
--// My specifications --
ASUS M4N68T-M LE
NForce 630a Chipset
AMD Phenom II X4 955 BE