Sure, no problem - you just had to ask..
Copy some custom fonts (with the right naming scheme) in to a dir named fonts on the user partition of the Kindle (check PN for a ready to go package), enter ;fc-cache followed by enter into the KTs search bar. Wait (a few minutes) for the screen to go blank and then reload your books (congratulations, you have installed custom fonts.)
Open a book and navigate to the fonts menu to see the new fonts displayed (by name) and selectable (by checkbox). Now activate the font size hack within JBPatch, configuere a custom fontsize set (f.e. beginning with 8, increments by 1 for every step), save, restart framework, go back into a book, navigate to the fonts menu, et voila:
and it doesnt show up in sent items ), if you havent, please leave a short reply and I will re-send it. Just don't want to flood your inbox.