Asus GeForce 9300M GS:
Chipset Model: Asus GeForce 9300M GS
PCIe Lane Width: x16
VRAM (Total): 256 MB
Vendor: NVIDIA (0x10de)
Device ID: 0x06e9
Revision ID: 0x00a1
ROM Revision: 62.98.76.00.01
Resolution: 1024 x 768
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
if the above, were displayed on a VNC session, you are very close to make it work.
it appears, it got the dev id ok, mean main kexts were loaded, but frame buffer was not loaded.
from experiences, not actual knowledge, i can mix fb kext from 10.8 kext with 10.10 kext.
there are lot of kexts pack for you graphics in difference site, down number of it , and try each fb kext from it.
(there people here, don't think it will work, i prove to myself i can use 8.0.61 fb with 10.0.16 kext for appleintelhdgraphics to get
qe/ci and full resolution on yosemite)
also from experience, i have use 10.8 patched kext for appleintelhdgraphics to get fully function
graphics from 10.9.0 to 10.9.4 (still using it).
you should also try, 9300 patched kext from 10.8.
before try anything else, try use disk utility to repair permissions and reboot from vnc session?
that was the last step i make 8.0.61 to load with 10.0.16 kext and get it working.