Download GemFX from here: http://www.twcenter.net/forums/showthread.php?672483-A-R2-TW-GEMFX-Version-1-0-9
Once installed in your dark souls "DATA" folder navigate to "\GEMFX\Presets\current" and replace the one in there with this preset:
That should be about it, feel free to customize the looks using the GemFX configurator also present in the DATA folder, everything is pretty self-explanatory.
The lightning and overall color scheme in DS1 can be very erratic and so i was unable to come up with something that provided a significant improvement for every area using GemFX. Basically, don't expect every area to look as good as firelink.
Not happy at all with how this one turned out but since i no longer have time to work on it i'm uploading regardless.