The Screensaver hack seems to work fine on the K3. I would definitely stay away from the fonts hack on the K3 until @NiLuJe gets the bugs worked out. A lot of folks are having problems with it, and when it does work the fonts tend to not look very good. The K3 apparently is much more tricky to hack as far as fonts go than the K2 and K DXes. Read the last several pages of this thread:

https://www.mobileread.com/forums/showthread.php?t=88004