There is no patch to enable the seperate sharpness slider, just one that enables the combined weight/sharpness slider for sideloaded fonts.
Starting from firmware 3.3.0 you can adjust the sharpness and weight for each font manually by editing the device's configuration file ".kobo/Kobo/Kobo eReader.conf". Once you have made an adjustment with the slider for a particular font, say Georgia, then the following lines will appear on the configuration file:
Code:
readingFontSharpness\Georgia=-0.0666666666666667
readingFontWeight\Georgia=0.1
The sharpness set by the slider ranges from -0.4 to 0.2, and weight from -0.2 to 0.8.
(Note: If you are using Windows, don't use Notepad to edit this file. Use an editor that understands unix line breaks such as Notepad++).