You have to make a shell script to replace the image assets in the app bundle.This should get you started on how to do that:
Solution:
get everything in project directory and open terminal and type "make" (with no quotes)
Create a directory in your tweak's root directory and name it com.yourname.yourcompanyname
Then move the contents of the "-" folder to the com.yourname.yourcompanyname folder
Inside that directory, enter a directory called DEBIAN and add your postinst, preinst, prerm, and postrm scripts inside there. Also, you have to take your control file from your tweak's root directory and copy it into ./com.yourname.yourcompanyname/DEBIAN
To compile do this:
Open MobileTerminal and type the following lines of code
su
alpine //or your root password
cd /var/mobile/tweakdirectory
dpkg-deb -Z gzip -b com.yourname.yourcompanyname Your deb will be unarchiveable
Hope this helps