If you are just wanting to change the lockscreen clock font, the easiest way is to rename your font file whatever you want to replace it with. I.E For JB, the lockscreen clock font is AndroidClock.ttf and to be safe I also replace AndroidClock_Highlight.ttf and AndroidClock_Solid.ttf. So change the font name that you want to use to those and put them in your system/font folder. Upon flashing those fonts will overwrite the existing ones and change the lockscreen clock font
That's a great idea. Wish I had thought of doing that. Guess it may be time for my first update lol